Clamping
If memory serves, the way this kind of thing works is the owner of the land wants to control parking, but not employ their own staff to set up the operation, so outsources to a "private parking control firm". These guys usually get to keep a significant amount of each clamp release fee, so are incentivised to clamp whenever possible.
It's the devils own bargain. I've seen a landowner arguing with the clamper about not fitting a clamp to a member of staff's car, the answer was sod off and read your contract.
Sooner they're gone the better ...