My post was an attempt at humour (lost on you, unfortunately) based on the fact that the driver of course would not be stopped literally "on the spot" as suggested, but more likely on the hard shoulder a few yards further along.
Fining middle-lane hoggers on the spot would be very dangerous ... imagine ... the police car comes up behind the hogger in the middle lane, stops him "on the spot" in the middle lane, gets out for a discussion and writes a ticket ... hellish back-up building in the middle lane behind the...