Although the security staff you come into contact with may be paid 5.73 an hour, there is a whole army of rather better paid bureaucracy behind them who need to justify their continued existence rather than let things stay as they are (ie be seen to be doing something all the time).
There are New Security Procedure Devisers, who are obviously out of a job if they don't devise new procedures, and there are New Security Procedure Devising Section Leaders and New Security Procedure Devising Managers in a structure above them. There are New Security Procedure Secretaries to type it all up, QA people, lawyers (inevitably), and everyone up the tree to the civil servants in Whitehall who play a part in pushing the paper round, on their own way to their index-linked gold-plated pensions, and maybe an OBE if they keep their noses clean.
Any connection between this and real, useful security controls is, of course, completely coincidental. And, of course, they expect us all to pay for it.