" Very surprised that they would accept that esp in UK "

Well - actually - Hertz already do.
If you use the HertzOnDemand product, you prove you have a licence at initial registration, then on every subsequent rental you merely press a button to confirm you still have a valid licence. It works fine.
If they can do it for the "OnDemand" fleet, would it be any bigger risk to do it for the regular fleet?