The idea seems quite sensible to me. However I would imagine Tesco have thought through all the options before going with the current one, and for some (probably technical as well as economical) reason ruled it out.
He certainly has it right that there are some EV owners seem to feel "entitled".
The charge I'd like to see is per minute plugged in as well as per unit. You could lower the unit cost such the combined amount more or less balanced with existing costs, and it would stop people leaving charged cars blocking charge points. It is in quite widespread use abroad so the technology/software exists.