i think for them its just frustration, their trying to get to a call as quickly as possible (which they never seem to do when you call them funny that eh) when they get stuck in traffic their natrally going to get annoyed about it.

but the fact remains that you can't break the law to move out the way for them so you just have to do it when you feel you can do safely, if they have a problem with that then they'll have to take it up with the system their working for.