How is it in the US, can you technically be fined for any speed that's over the limit?
Here it's like this: there is a "technical deduction" of 3km/h (1.8 mph) from what the radar reads. If the speed after this is less than or equal to 6km/h (3.7 mph) over the speed limit, you'll be issued a warning.
Up to 10km/h (6.2 mph) over the limit is a 100€ fine. Up to 15km/h (9.3 mph) is a 150€ fine. Up to 20km/h (12.4 mph) is a 200€ fine. After that it's decided based on your income. If you make a lot of money (and stupidly have it declared as wages), this can be tens of thousands...
Finland, Home of the $103,000 Speeding Ticket
When I drove a bit more for work (up to 50 000km/year) I got some of those "big" fines because the country roads alternate between 60 and 80 seemingly by random, it's hard to keep track of it in the dark and with no other traffic... Mine were only a couple hundred though. I always complained about not being able to pay them so they got them from me 20€ per month over a couple of years...