Re: This should be one of the easiest taxes to collect ...
ANPR camera at every petrol station. No current record, no petrol (and maybe the drive-off barriers come up for good measure).
Loong list of problems with that one, starting with the fact that tax dodgers tend to be rather good at, umm, "borrowing" license plates of others. On the plus side, this could please UKIP as no foreign plate could get petrol either..