Retirees still have an income (public or private pension), as do (in civilised countries) the unemployed (in the form a dole/unemployment benefits), but yes, a minimum charge + extra seems to make sense (perhaps with an exception for homelessness.

> ends up just being a punishment for having a good job.

No; it's a punishment for breaking the law, with (ideally) the punishment scaling to create a similar deterrent to everyone in the society.