In regards to war casualties, I'm going to be a bit cruel (IOW, realist) here, because the truth is cruel.
Americans didn't have far fewer casualties in World War 2 because Asians and Europeans (I am speaking in geographical, not racial, terms here) just suffered more. Americans had fewer casualties than the other combatants because the other combatants were fucking awful at training and supplying their soldiers.
Take the Imperial Japanese Army. They carried single shot Arisaka bolt-action rifles with fixed bayonets, and a standard tactic for much of World War 2 was firing followed by a "banzai charge". This was not because the Japanese Army were somehow hugely primitive, but because this tactic worked in actions against Chinese opponents armed with similar rifles. And Japanese army training consisted in large part of brutalizing a recruit into possessing unquestioning obedience and endurance in the face of privation.
In contrast, American Marines were trained in the use of specific weapons, were issued as a main arm the Garand .30-06 semi-automatic rifle, with an eight-round clip that automatically ejected, and were taught tactics, land navigation, and equipped with squad weapons suitable to jungle and island fighting. And rather than train a Marine to simply do without, American logistics usually ensured that troops were supplied with enough (if often rather tasteless) food. That's not to say American troops didn't starve - they did. But they went home looking like they'd been malnourished. The Japanese sometimes starved to death.
Which meant that when Americans went up against the Imperial Japanese Army, they tended to achieve KIA rates of anywhere from 1-3 to 1-10 in the favor of the Americans, even on ground entirely favoring the IJA. That's not patriotic bullcrap, it's just history.
On the same level, the Russians confronted the Nazis while possessing many of the same disadvantages. Results were often similar, with the opposing downside for the Germans that their homefront was far inferior to the American one, which supplied itself, the Russians, the British, the French Resistance, and even, sometimes, the Chinese. And when the Nazis went up against the Americans, American and British tactics were still superior, as was most of their equipment, including the Sherman, when understood in the totality, including such things as production costs (two exceptions: the German infantry machinegun (mg42) and infantry anti-tank weapons were better). Aside from those two things, American planes were better, American guns were better, American tanks were better (in terms of war effect, rather than relatively rare tank-to-tank combat), and American artillery was better.
This is my preferred area of study, and I am not saying these things because I am an American. Indeed, part of the reason American equipment was better was because we shamelessly stole everything we could, such as collaborating with the British on the P-51 Mustang.
But when it comes to low casualties, the reason American casualties were so low is in large part because American logistics and production were so good. Where a German commander might be able to order a 10 minute daily barrage, an American commander could order one wherever he found resistance - and with proximity detonation shells to boot. Where a Russian commander would order divisions of bolt-action riflemen forward, an American commander could fire an artillery barrage, then move forward under a moving mortar screen, with his squads equipped with flamethrowers, bazookas, BARs, Garands, Thompson submachineguns, and with accompanying tank support, on a smaller front. As you might imagine, this greater expenditure of ammunition resulted in smaller loss of life. If that weren't enough, the fact that surrendering to Americans, Canadians, and British soldiers meant time in a POW camp far more comfortable than war-time Germany probably reduced the desire to fight to the bitter end.
In other words, and to put it cruelly, the reason Americans didn't have the same experience of war as Europeans did isn't just because of geographic isolation, it's also because they were just better at killing people without getting killed, usually by the expenditure of a truly enormous amount of ordinance that no other side could afford.
But it's not just that. Let me give an example.
Take U.S. carriers. In World War 2, naval combat transitioned to carrier combat. While it is true that the Japanese started the war with a carrier strike at Pearl Harbor, it is less well known that the foremost pre-war advocate of air power was Billy Mitchell, a U.S. serviceman. While he was court-martialed, that was more for being an ass than being right. And American carriers reflected this. Unlike British carriers, American carriers were designed with "soft decks", that is to say, they were designed with wooden decks to allow quick repair of the flight deck (theoretically), and a larger complement of aircraft. While this might seem odd, what it reflected was the understanding that the only defense a fleet has is to get planes in the air, and if you cannot repair the runway quickly, you are fucked. To make up for this, American hangar decks were vented and open to the outside air - preventing fume build-up, and American damage control was decentralized and relied on massively redundant systems, water-tight compartments, and extensive and unending damage control drills and training. American carriers had crash barriers - which meant less time clearing flight decks, and American carriers also avoided fueling planes on the hangar decks, which also prevented fume build-up. Oh, and American AA (anti-aircraft fire) was computer controlled, and the American attitude towards AA capability was such that some observing it thought that the ships firing were actually on fire - in other words, as many AA guns as you could fit on a ship. Any ship. And American AA shells had proximity fuses not long after Midway.
Meanwhile, Japanese carriers had two hangar decks, which they would fuel on, enclosed in a hull which would become rife with fumes. Their magazine elevators and procedures often ended up with them temporarily storing weapons on these same barely-ventilated hangar decks. Some Japanese carriers had only two mains for conveying water for fire-fighting, which could both be easily knocked out. And while the Japanese started the war with elite pilots, their training system was inferior to the American one, as was their flight control, their radar, and their radios. Some Japanese pilots removed their radios to save weight, they were considered so useless. And when it came to sending aircraft out, Japanese pilots often did not carry parachutes, and flew planes without armor or self-sealing fuel tanks for the majority of the war, in the majority of situations.
If one were then to comment that Americans don't know what it's like to lose a major carrier battle, I think Americans might well be pardoned for raising an ironic eyebrow.