The UN is partisan, let's ask the BBC, oh hang on.The UN’s 90% figure on Gaza’s residential buildings is unverified by independent sources due to restricted access as you have stated. So we can't verify this.
If it were true then context must given. Hamas’s tactic of embedding military assets in civilian areas complicates strikes and causes damage.
Maybe we can ask Hamas politely to move their base of operations into the open. Or better yet surrender and give up the rest of the hostages. That way there would be no excuse for Israel to continue.
If 90% is correct then around 2 million people would be in tents, that would be all over the anti Israel media, and there's no sign of it.