oh please TSR2, lighten up, no offence intended.
Mr Gayrugbybloke has the right idea.
The 'lazy ar$e' thing is actually a quote from a member of GMP who is a mate. When I asked him about this oddity of airport architecture, it was he who told me that very reason using those very words.
There is no valid reason why thousands of passengers should be inconvenienced for the convenience of GMP.
No doubt that catch all phrase 'in the interests of security' will be trotted out as the official reason for such poor consideration.