Apple has to comply with different country regulatory bodies. So Apple does in fact limit the signal strength and bands it uses based on what country you are using the AirPort Extreme in.
As to how they do that, as far as I know its not based on what you plug in as your location in the setup, they have different units that they sell.
Besides, if you are caught with a non compiling unit you could have your unit taking from you, face a fine or even jail time!
As for an an example some people had problems with their iPads when they first came out entering some countries and were taken from them as Apple hadn't gotten the needed certificates from some countries for their use.
Here's a useful link Microwave Exposure Limits by Countries. In it you will find the Ukraine emissions standard.
Just so you know you can use multiple units inter-connected in case you have a very large building (or open space). Just place them 1/3 the distance apart of the size of the building.