How many unenforceable laws do you want? Most laws are poorly enforced or aren’t enforced. Personally I don’t want them in my country, but at 67 I have yet to have encountered a transgender in a restroom.
Why is it an unenforceable law? The reason you haven’t encountered one yet is because it was socially unacceptable and they would be prosecuted under other laws.
There is a movement to force acceptance and legalization of this activity. This law is intended to counter that move.
Its intended to protect the children, not the 67 year old.