From what I have heard and read about the "TV without frontiers" directive (or whatever it is called, which applies to all of europe) is that any TV signal that you can receive FTA you are allowed to watch, show to the public (eg in a bar) or retransmit freely.
Retransmit freely was restricted to frequency ranges you are allowed to use in the country you are in (so not on UHF/VHF in the UK etc) and freely also meant not encrypt and make a profit from. If the original broadcaster does not have the rights to broadcast their program in the second country it is not you the rebroadcaster that is at fault for showing the channel, but the initial broadcaster for showing the channels FTA in the second country at all.
Now that would make it look like the BBC channels can be rebroadcast legally, if you are using a legal frequency range and don’t make a profit from it.
But already that looks like the rebroadcasters are breaking the law by charging people a monthly subscription. However they may be able to pass that off as ‘equipment rent’ or something if the channels are still being broadcast FTA.
However the rebroadcasters cannot broadcast ITV/Ch4/Ch5 or any Sky channels, they are not FTA. There is no way of getting a card that will legally allow you to broadcast these channels abroad, ITV/Sky etc do not have the rights to broadcast their channels outside the UK, if they did they could post cards straight to subscribers in these countries.
How these rebroadcast networks have been given a legal status I don’t know, and would be interested to find out. It could be that the authorities were misinformed (by the rebroadcasters claiming that all the channels they were showing were FTA etc). It could be that the laws are very lapsed in some areas. It could be a brown envelope filled with notes arrived on the doorstep of an important person, or it could just be that the rebroadcasters are claiming that everything is now legal now when in fact nothing has changed.
If any of this is wrong please correct me, this is just taken from things I have come across now and then and may be outdated (or never correct). Also if anyone knows how these rebroadcasters claim to be doing it legally please let me know also.
Anyway rebroadcasting is a legal nightmare, unless you are very sure of what you are doing and the laws, or just want to run for as long as possible without getting caught, I would stay well away from it.