Should I replace this cracked bathroom wall tile?
I had posted this as a comment but believe it should be an answer.
Wow to me from that photo this is a full blown broken tile not a hair line crack that you would see in a natural stone. This porcelain tile should have no broken tiles. I hope you have not made the final payment and if you have contact your local contractors board this is unacceptable in my opinion and not a hairline crack. It looks like they used snipers and not a saw to make that crappy cut out. Just my opinion but it looks like a DIY job for a first time tile person to me.