Hi, as far as I know, dog catchers are paid a basic salary, not on the amount of animals picked up. There are laws in place for the licencing of a dogs, however, as with most laws in T&T, there are just not enough police to enforce it. At the moment TTSPCA & AWN are working with the Law Commison to update the Summary Offences Law; and increase fines, as well as updating the outdated laws regarding animals and the way they are treated.
There isn't enough police or enough police willing to do it. Animals are not high on anyone's list here. Besides little messages like this online I really don't see any big impact from animal activists locally. People generally care for their own pets and that's it. An earlier suggestion about a part of the police specifically trained for this might be a help but still you have to get people that really want to do it.