I stand to be corrected by ATCOs but is it not partly true to say that the large number of CAS infringements is a result of improved radar and increased use of transponders by light aircraft. Gliders are less likely to show up on radar due to a universal non-use of transponders. As I bimble about I often hear controllers advising of traffic that could be gliders or microlights. I do understand the argument that gliders rarely have enough power or room for transponders.