Here's my two penneth as an outsider.

Photography has taken off and increased in popularity over the years.
Since the introduction of digital images, it has become easier and more affordable to take part.
Once the hobby of a select few who could afford the kit and could arrange for their photos to developed, young kids are joining in with cheap digitals, teenagers with a bigger disposable income are becoming more adventurous with the kit they have and twenty/thirty something's can afford to take part too.

Around the same time, the anti-terrorism laws started coming into place.

Paranoia started to increase with members of the public becoming concerned about either themselves or young kids appearing in shots.
Human rights is suddenly a buzz word.

Over zealous officials, either under a self of importance or paranoia, will stop whoever they fancy from taking photos, whilst not understanding the rules or regulations in place.
Whilst at the same time, bosses state no public photography is allowed - record our movements with an endless supply of cctv recording equipment.

All of this, coupled with one or two over enthusiastic enthusiasts, running around bus stations going to places they shouldn't be and officials worried they are going to face corporate manslaughter charges.
A reactive organisation, once aware of incidents suddenly become paranoid about possible outcomes.

The end result?

Exactly what the photographers amongst us are facing now.

Forms may be filled in, granting permission, but once too many of those are completed, we end up back at square one.

Time to be more adventurous and creative with photos I think.
The days of bus station photos appear to be over, no matter how frustrating it is.