With how "smart" modern EV cars are? Shouldn't be that hard to set up accounts, have the data uploaded and money taken by DD.
But I guess only issue is of non-payment or "owner" errors.
Yes ideally agree
There are other issues though, do you just do something that uses ANPR type stuff on main roads, forcing those budget conscious to sideroads.
Do you have so many of these ANPR thingies that you cant basically go anywhere without them recording the usage so that you can be charged. Every junction maybe?
If not ANPR but say a chip type thing, how do you avoid all the hacks that will be a significant market if the charge is significant.
If using ANPR how to stop plate cloning etc
Basically anything that relies on recording will be liable to being hacked if its significant.
As I said, its well recognised that collecting tax at the time of supply is far easier to ensure high levels of compliance and far harder to consistently cheat than retrospective actions
You'd need a decent size solar setup over the winter - approx. depending on a few factors like the specific EV, conversion efficiency and where you were in the UK, etc. a 4kw solar array would average around 10-12 miles worth over a whole day during the darker months - sometimes you might get whole weeks where it doesn't manage that total.
This is my point, it would be uneconomic to attempt to do enough for the winter months, and certainly for the forseeable future it would be no bad thing to pull less from the grid as its not going to be fully green for a long time in reality.
If a significant portion (I dont think they ever would but..) decided to avoid the duty or premium then you can always switch the tax collection at that point.
If you really wanted to avoid excessive self generated electricity being non premium units if used for car power then you could easily apply the same rules as for people making their own biodiesel, the same tax is due even if you do it yourself. You are liable to report the usage and pay the duty.
Anyone not doing so would be in trouble if caught.