They beep when you go above the speed limit, and only for a couple seconds. If they do that 'constantly' the problem is in the driver's seat...

It takes two seconds to turn off in my car (though by law it has to reset on every drive), but I never bother. In situations where it's "ok" to drive a little over the limit, it's a small price to pay and a gentle reminder.

The car probably doesn't have perfect knowledge of speed limits across Europe.