I like to sing in the shower because I'm terrible lol.
I think most people enjoy singing in the shower! It's a pretty widespread phenomena.
I believe it has to do with the way the sound reverberates, also because other people can't hear.
You are spot on! Most people do sing in the bathroom because all of the hard wall surfaces and wooden panels block the sound.
What are some other places people like to sing?
Besides people singing in the bathroom since centuries ago, people have also create things like Karaoke where they can sing!