It's an open question. In Scandinavia, they apparently scale fines based on wealth: https://www.theatlantic.com/business/archive/2015/03/finland...
It is important to be able to sufficiently deter people from committing various crimes/infractions, and this is one way to do it. In the US, we have "points" that go on your record, which means that rich people can't get speeding tickets that frequently — you eventually lose your license. And if you're going 25 over the limit, you can be charged with reckless driving.