Cubic feet would be better, especially as taller vehicles are more dangerous to pedestrians.
Let’s ban archaic units like feet and stick with cubic meter.
Plus there are vans, so the more accurate metric would be a cubic meter per passenger.
Yeah, and just register it in a database. Like how I gotta pay $100 more in vehicle registration because my car’s 50 fucking kg above the lower bracket. People with F350s can pay triple what I do. No, sextuple! Because they can’t fit in just one park. Parking inspector puts in the number plate and machine calculates the rest.