What's the point of parking spaces?

When no one sticks to them? After reading Alan's post on 4x4s parked badly at Sainsburys, it reminded me of something that's really got on my nerves lately, people that park in parent and baby spaces, that have no children with them, sometimes even be a work van!
The worst culprits seem to be found at Tesco Banbridge and although security have advised to complain to management, they claim it keeps happening and nothing is ever done long term to resolve it. What's doubly frustrating is that Tesco have a parent and baby club which they get you to sign up to and in return, give you a "parking pass" of sorts to allow you to use these spaces. A good idea in principle, but I've never noticed anyone use them, but besides that, what's the point of this scheme if it isn't going to be enforced?