Advance for regular buses?

Hello municipality, daily experience on the road: A bus wants to thread itself out of the station bay into the flowing traffic. In my opinion there is a rule, which gives the “line traffic” the priority, but it must not force itself in the event of an emergency. So generally wobbly thing…. Is that really so, MUST I stop as a driver accordingly, if a bus wants to drive off noticeably? Next: What counts under regular traffic; the inner-city lines, Overland lines, school buses, long-distance travel lines? How is it distinguished there? Personally, I have no problem in letting them slip in, on the contrary; I am concerned with this question purely about the principle. What do the experts say about it?