What's the point of jail?

We spend so much tax moneh on it and jailbirds still can't be enslaved anymore in America. I get why it used to be a thing back then because it was slavery by another name. But now that times have changed, why are prisons used and no other forms of punishment? 🤔

If someone steals a bike or breaks someone's glass or pushes someone, why do we take years from their life instead of just simply punishing them? Do you know how long years are? Even worse, they network with other criminals even worse than they are and they're not in there teaching each other to behave 😂

Why do we take years and decades from people's lives in response to something small or simple? ,_,