That is indeed an exception, but IIRC it's not the only event with that exception: I think the world, continental and national championships also don't allow te

That is indeed an exception, but IIRC it's not the only event with that exception: I think the world, continental and national championships also don't allow team radios. Another exception is that the Olympics and world and continental championships are ridden with national teams instead of the various commercial teams. That makes quite a difference too.