system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do people in the UK/CA and many other places say "in hospital" instead of "in the hospital" yet, they don't say "In library" or "in supermarket?"
gpt
I live in the UK and never thought about this. 

Trips to hospital imply a long term event but a trip to a shop is more temporary. 

I guess it's because you can be hospitalised but not libraryised or supermarketed. When you are being educated you say you are in school not in the school.  

Essentially it's our language and we will do whatever the bloody hell we like with it (joking)