While speed limits are posted, and you could get pulled over by a cop anywhere for speeding, most of the time there is not a cop around and you can get away with speeding 95% of the time you drive. And with many roads the flow of traffic exceeds the posted limit - so just keeping up with the flow will mean you're going 5-10 over the limit.
But with speed 'traps', there's a concerted effort to set up places where police can hide relatively well, and wait for speeders to come through that spot, pulling over often handfuls of drivers at a time. The most onerous speed traps are sometimes designed to bring in revenue - pulling over people for driving 1-5 MPH over the limit...some cities or towns are known for having sudden drops in the speed limit where you are traveling in a 55MPH zone, come around a bend, find a sign announcing speed limit is 45MPH, and the moment you pass that sign, there's a cop car hiding behind a tree to pull you over before you could even reasonably reduce your speed.
Florida has quite a few smaller towns known for this tactic - the locals mostly know about them, but outside visitors may not. Down here in SE Florida, the town of Parkland is very well known for issuing tickets at 2MPH over the posted limit, and keeps the speed limits at 35MPH even on wide open, straight roads with no cross streets. If a resident has a parkland town sticker on their car, they have a little more leeway in the 1-5MPH-over range, but if not, even 37mph can get you a ticket. And often, the cops like to pick places where they can hide a bit so you don't see them until you are passing them. That's a classic 'speed trap'.
Decades ago, Florida state troopers used to employ a tactic at the Florida border nicknamed 'jaws' - they'd line up 5-6 cars on either side of the road, diagonally pointing downroad (median and right side), all partially hidden by the big 'welcome' signs, so people entering the state from GA going over the speed limit wouldn't notice until too late - and those cars would jump out one by one, each pulling over their quarry. It was not uncommon to see 8-10 people pulled over at once, then they'd all go back into position like teeth in a shark's mouth, to snag their next speeder.