Same reason they're attacking universities, medical research labs, power stations, bridges, hospitals, paramedic teams, civilian rescue teams...
With this particular incident with apparent US strikes on a school adjacent to a military complex, and formerly part of that military complex, you would think it must be obvious to any reasonable person that we did not knowingly target a school.
Yet here we are.
We are so far past there being any merit to “Israel would never knowingly target civilians/children/hospitals/etc” that you just shouldn’t even bother. Just own it, if your leadership thinks the only winning strategy is the annihilation of another people, or at least their complete displacement, own it. Stop trying to hide behind “it was a mistake” while simultaneously showing you have no issues putting a missile through a singular car window to assassinate people labeled an enemy. Nobody buys it anymore.
They should have known, so it may still be a war crime. https://www.prospectmagazine.co.uk/ideas/law/the-weekly-cons...
And if it was an accident it only gives us more reason to oppose the whole operation. Why should we believe what they think they "know" about uranium stocks or anything else, if they couldn't figure out a building has been a school for 10+ years?
I also wonder if they really should have known by the second or third strike, but I can't readily find whether they had a live visual or anything, so probably did not. Arguably you can't in good conscience strike a target you can't see well, but I'm sure it happens all the time and doesn't usually go this bad.