I'm sure they used to have stickers on the back at one time saying "Please let buses pull out" - I don't know if that ever worked. They certainly don't let you pull out nowadays. Half the time we have to force our way back in to traffic - if we waited for the kindly soul to let you out, we might as well tear up the timetable we are trying to keep to.to put up with.
I was taught to drive by my Father, who was a bus driver for EMMS - therefore you need to wait for me as I always let buses pull out!

As for "seeming lack of mirror use and indicators" - if you cant see my mirrors, I can't see you. Buses have blind spots as do many large vehicles. Sometimes we can't see whats going off behind us - fact. This gives us a bad reputation.
Whilst my dad was a bus driver EMMS had a fleet of Bristol RE single deckers and they had a floor level window in the back door, which enabled drivers to see what was immediately behind them. He could never understand why that idea was never universally adopted.