There seems to be little evidence to your statement “Israel seems to trying much harder to avoid civilian casualties than […]”. All estimates I have seen seem to indicate astonishing rates of civilian casualties, hence why Israel is getting so much criticism of basically indiscriminate killing in Gaza…

Even though you may not be necessarily wrong on how little regard those armies in those previous wars (and indeed all warring parties in those wars to some extent) had for the civilian population, the situation is Gaza is made so much more drastic because there’s already nowhere for the (already displaced for decades) population to go amid all this assault and bombing (not to mention the widespread starving and all those other factors, which combined led to the “genocide” claim levied by some). That’s also a reason why all western countries are trying to dissuade Israel from the Rafat assault.

Also, we have the idea that human beings are supposed to learn from those previous tragedies and do better, and that we’re in a much more civilized, peaceful and prosperous place than before, so it’s likely a disillusion and horror for a lot of people to see such a nightmarish scenario unfolding again in 2023. Some intrinsic parts about human nature and human societies will never change unfortunately.