We got involved in one of those heading out to North Padre Island on a Memorial day weekend some years ago.
The road was backed up for miles so, they posted cops under the overpass for people exiting to get out of the traffic,looking at every car.
Pretty chicken chit if you ask me.
I saw one in Roud Rock a couple of months ago on old Settlers drive in the middle of a workday. (not just for seatbelts)
The APD crotch rocket cops like to sit under the 183A overpass where the last free exit from 183 is at Lakeline. They catch a lot of drivers coming from 620 turning left onto Lakeline - from the straight ahead only lane. I almost had a lady turn into the right side of my pickup there.