They didn't do anything because his dad wasn't violent towards him he was just a drunk. Everything that caused him harm was his unlucky aura or bad luck. Like things falling on him, the soccer ball hitting him etc. That's why he was so nonchalant about his injuries. It wasn't his dad doing him harm. He even says he was slightly caught by the bottle flying, so the bottle wasn't aimed him or would have hit him straight on. His dad probably threw it towards the trash or a corner and Fuji's unlucky ness put him slightly in the way. That's why the dad is written kind of comically if u noticed when he actually makes his appearance. His just a drunkard drowning in his wifes passing.
Neglect IS abuse though. If his kid is getting physically injured because he can't be bothered to dispose glass bottles safely, that's on him. Doesn't matter if he's heartbroken over his wife, he still has a kid he's responsible for.
It makes me sad though that no one did anything to help Fuji beyond "oh did your drunk dad hit you again" :((
But I'm glad he has great friends and him and his boyfriend are so cute.