it will be simple to tell the difference between a school bus and a tank. the school bus is full of young people, most of whom don't want to be there, many of whom are there simply out of some sense of obligation to their families or society, or because (depending on the country) they are legally required to be there. they may (again, depending on the country) be in uniform.
simple.

One of the other potential issues that doesn't seem to be considered here is the likelihood that, when one side (ours) has sufficient robot-fighting capacity that flesh-and-blood soldiers in combat zones becomes unnecessary, then a certain level of tactical conservatism gets thrown out the window. It seems that there would be more opportunities for those in charge to simply deploy automatons rather than seek out less lethal means of settling disputes. Part of the reason diplomacy has traditionally been a first, rather than a last resort is that if successful, it prevents a great deal of blood from being spilled on both sides. If we reach a state where essentially no blood will be spilt on our side, then not only might WE become more prone to, "kill 'em all and let God sort it out", but conversely, it puts our adversaries in the position of shifting their targeting opportunities even more against non-combatants.

Blowing up robo-soldiers might be expensive, but clearly it wouldn't have the same psychological effect as taking out an office tower or two, as events have sadly shown.

One of the other potential issues that doesn't seem to be considered here is the likelihood that, when one side (ours) has sufficient robot-fighting capacity that flesh-and-blood soldiers in combat zones becomes unnecessary, then a certain level of tactical conservatism gets thrown out the window.

Huh. I thought it was pretty obviously considered in the phrase, "the loss of soldier’s lives is the single greatest factor making the American public reluctant to wage war". I mean, you know, shades of meaning. But I certainly thought it was implicit.

Joshua,

That certainly does imply expectation of a more er, "liberal" combative stance on the part of the public, although I was thinking more along the lines of actual military tactical issues, but your point is well taken.