Very much this. How many times do you go along a 2 lane carriageway with cars in both lanes. then it becomes 3 lane by the addition of a new inside lane and everyone stays in their lane, leaving the inside lane completely empty?
I was driving in my car up the M23 early on Friday and on approaching the Gatwick junction, a car came down the slip road in front of me and moved straight across into the right hand lane. It just seemed weird as we were the only two cars as far as the eye could see.
They are the ones that are working. Empty lorries go flat out uphill while full ones may go 25 MPH slower. Most drivers have just enough time to get home, slow them down and they are stuck in a lay-by all night. Why pick on lorries, why not just let the cars stick to one lane they have no time...
It doesn't really matter if it's enforced or not. As long as it brings to the attention of some people that blocking motorways isn't a good idea then it will have helped.