Here, you don't have to go to court if you're just paying the fine. You might have to pay at the courthouse but you don't have to plead guilty in front of a judge. It's already opt in.
It can also be a problem if people are persuaded that it's not worth fighting a bad ticket, for example if the total cost is higher when you contest the ticket (court fees).
Apart from the algorithmic determination of the fine, it sounds much like the system of "administrative punishments" in place here. Which is, unfortunately, biased against you by presumption of guilt and further biased because hiring a lawyer for a proper defense would cost as much as the fine.
I have heard horror stories about people having to pay hundreds/thousands of dollars in fees for parking tickets and stuff.
I watched a documentary about it a while ago and some people actually end up homeless/in and out of prison for not being able to pay the fees that come along with some fines. They can pay for a speeding ticket, but the administration fees are sometimes double or triple the cost of the ticket, and keep going up and up the longer you wait to pay.
It is opt in though. If I didn't pay for my train ticket and got fined, I would much rather do it online than go to court. If it was something ridiculous like being caught fishing without having a license on me, but I actually did have a license, I wouldn't opt in and I would go to court instead.
It only becomes a problem when people don't have the option to contest it in court.
edit: I do think this is a good idea, but maybe it wouldn't even be considered if our police force wasn't vastly underfunded.