Good. Now, we have an active act of non-compliance with an (hopefully? please?) existing law that forces you to buckle up. Let's start the fines with 1k and see if this helps, if not, go up. Not buckling up is so insane, I cannot even begin to imagine it ..
Given that person is only harming themselves, it's totalitarian to apply a fine here.
If someone makes such a deliberate and conscious decision not to wear a seatbelt, maybe you could assume they have their own reason for that.
It's not even clear that forcing people to wear a seatbelt saves lives. It may increase the risk to other people, if people are seeking out a level of risk that they're comfortable with:
https://en.wikipedia.org/wiki/Seat_belt#Risk_compensation
They're not; they risk harming other people in the vehicle and there is extra effort to recover the injured body of someone from an RTA if that person wasn't wearing a seatbelt which puts emergency services at increased risk of harm.
I'll repeat my point in your terms: By forcing people to wear the seatbelt, other risk-taking behaviour is increased, which appears to result in more RTAs.
The evidence on either side is not enough to justify bankrupting fines.
