In the US the regulations on the monitors and similar low power transmitters are there but nobody from the FCC really tests them unless there is a problem. The company must comply with Part 15 by transmitting no more than some small amount of power (500mw. I believe) and then the company certifies and is taken at their word. The FCC is too busy auctioning spectrum for huge amounts of money to spend their time making sure there is minimum possible inteference, it is simple return on investment calculation.