Why not address the actual problem: ability to drive responsibly? Otherwise you’re just creating another privilege for the wealthy. Licensure is already an established practice.

Edit: I do want to clarify that I’m not entirely opposed to taxing them if needed. There should be fewer of those vehicles on the road. I’d just rather explore ways that don’t further exacerbate wealth inequality.

Just make car registration fees proportional to the odds of killing or injuring someone:

Cost ∝ mass² × blind spot ratio

You could also add another mass⁴ term to compensate for road damage.