Those warnings are rarely given, and also warning someone that you're about to bomb their home and store and hospital and aid and aid workers, doesn't justify the crime of doing those things.
If all innocent civilians are equal, then it's not acceptable to kill 35,000 Palestinian ones to avenge <2,000 Israeli ones, or even to prevent another <2,000 future Israeli casualties. That math makes no sense from the outside perspective, unless one discriminates based on race, or otherwise believes Israel civilians are somehow more valuable than Palestinian civilians.
As for "sympathizers": someone disagreeing with you doesn't justify exploding them, either.
If all innocent civilians are equal, then it's not acceptable to kill 35,000 Palestinian ones to avenge <2,000 Israeli ones, or even to prevent another <2,000 future Israeli casualties. That math makes no sense from the outside perspective, unless one discriminates based on race, or otherwise believes Israel civilians are somehow more valuable than Palestinian civilians.
As for "sympathizers": someone disagreeing with you doesn't justify exploding them, either.