It always amazed me how London buses stopped at every stop, even when it was clear nobody was getting on or off (does it help them reset their GPS or something?)
It would more than likely be a TfL requirement of some kind I would imagine, they are very specific about certain points (such as the daft decision to insist on destination blinds which show ONLY the destination, not any intermediate stopping points; very tourist un-friendly!)
Unfortunately there are many places where far too many buses are expected to squeeze into far too little space, with the inevitable chaos ensuing. This is often symptomatic of local highways departments and suchlike who have no working knowledge of the facilities you actually need to cater for buses, and base their efforts on sometimes rather silly assumptions. One example which I always found exasperating was the blanket fitting of raised kerb edges at all bus stops in my area, even at short pull-ins where the only way to get anywhere near the pavement is to approach at an angle and swing the front end over the kerb before straightening out. So the council helpfully install a bloody great raised kerb, meaning you can't swing the bus over it any more, and instead have to stop miles out in the road! Great :roll:
When I was a driver I would always make a point of ensuring that I slowed down and made whatever reasonable efforts I coule to make myself visible to passengers if a stop was congested. If it was totally invisible behind a line of buses I'd generally pull in anyway and give any intending punters the chance to walk up. Sadly there will always be drivers who can't be bothered to do anything remotely helpful, and operators who will set such tight schedules that any opportunity not to stop is likely to be snapped up.