Disagree, that is a person not paying attention to the laws of the road and not obeying them. Once you reach the speed limit sign you need to be doing that speed. The speed zone begins where the sign is at, so if you're going from a 40 mph zone down to a 25 mph zone, once you reach the 25 mph sign you need to be doing 25 mph. Not start to slow down when you pass the sign. That is not a trap that is not obeying the laws of the road. Again, a "trap" would imply that the officer put you in a position to speed and then wrote you the ticket after the fact.There are situations where the speed difference is immediate and police have been waiting to write a ticket. That to me is a 'speed trap'
There is a vacation spot the family and I go to yearly, and along the route there are several small towns along this major state route, so the speed limit goes from 25 to 35 to 50 back to 40 down to 25 back to 40 up to 50 back to 35 down to 25 etc. as you come and go through the towns. Its really annoying, but there is no "speed trap", because as a driver you need to be paying attention to the road, and if you're doing so you'll see all the speed limit signs and be able to follow them.
All the officers I know won't even pull a person over unless they're doing like 10 over, and some won't unless they person is doing 12-15 over. Per the law, 1 over is technically a moving violation, though no officer would pull a person over for such an offense. So if you're doing 10-15 over then you should expect the ticket, and not give the officer grief because they are "harassing you", "targeting you", put you in a "speed trap" and my personal favorite... "thanks for ruining my day."
If people just gave themselves a few extra minutes to get ready for work or for school or whatever it is there driving down the road to go to... they wouldn't have to speed and drive like an idiot to get there on time. Everybody is always in a hurry these days. It's annoying.