There’s certainly an argument for it. Mileage is noted at MOT time anyway so they could charge then.
VED seems very arbitrarily calculated to me. I drive a Defender and pay the top rage of tax, it’s over 700 quid a year. But if I bought a van variant, or a the exact same car registered in a different year, the rate would be lower.
Yes it’s an old Land Rover that spews out a lot of shite and pisses oil all over the road so I’m more than happy to pay a higher rate than most, it’s only fair. But it’s these opaque and convoluted changes to the way they work it out that annoys me.
Similarly I’ve previously had a little Fiesta that cost 5x more to take than my BMW that weighted twice as much and had an engine 2x the size.
Charging by the mile seems a very sensible approach to me.