ELI5 why is it that we can structure a sentence like “I’m in school” but not “I’m in nightclub”?

Some nouns have to have “the” before it but seems like not all of them need it, so any explanations would be helpful!

edit: wow, didn’t expect so much traction on this. Thank you for your explanations! Interestingly, I’m actually a native English speaker but don’t really know grammar terminology all that well. Thanks for sharing your knowledge!