The idea of jail is that your personal freedom is taken away as punishment for a number of days. How much opportunity cost those days have, or how much money y

The idea of jail is that your personal freedom is taken away as punishment for a number of days. How much opportunity cost those days have, or how much money you lose as a result of your jail time, is irrelevant. The punishment is taking away your personal freedom. Jail time is a fair punishment: Nobody likes having their freedom taken from them. There is no need to scale it. But its different for fines. If you drive a 100k€ car, you're not going to give a shit about a 50€ fine for speeding. And my personal experience seems to suggest this is true: Drivers of expensive cars often ignore speed limits and "no parking" signs. So one thing we could do is add a mandatory jail sentence for speeding. You drive to fast, you go to jail for a day. But that seems a bit harsh, so maybe we stick with the fine, but make it so that it also hurts people who make a lot of money.