And this case was about people who had gone through entire non-trivial justice system processes for non-trivial crimes, were convicted, and later had those convictions overturned. It's not about fines and speeding tickets.
Thomas' opinion is very strictly based on the idea that there was once a legal conviction, that was then overturned. That's not something that happens very much in the legal system, and it particularly doesn't happen very much for the small annoying offenses like traffic violations that you're talking about, because it's just not worth the time and effort to overturn them.
He didn't say, "It's cool to fine someone absent a conviction, and then when or if they successfully avoid a conviction, do not give them back their money."
> The Justice Department's report said Brockmeyer approved the creation of additional fees, "many of which are widely considered abusive and may be unlawful, including several that the City has repealed during the pendency of our investigation. These include a $50 fee charged each time a person has a pending municipal arrest warrant cleared."
> Just about every branch of Ferguson government -- police, Municipal Court, City Hall -- participated in "unlawful" targeting of African-American residents for tickets and fines, the Justice Department concluded.
http://www.cnn.com/2015/03/09/us/ferguson-missouri-courts/in...
It looks like it was trivially easy to come up with any scheme they wanted to collect money from people too vulnerable and poor to fight it. If the Michael Brown shooting hadn't happened, the area wouldn't have received the scrutiny it did, and my assumption is that the scheme would still be ongoing. I'm sure this happens elsewhere; the smaller the community and the more chummy the players, the easier it would be.