Anno I agree with you that may be the case with large corporate employers.
But most small employers struggle against increasing burdens of bureaucracy, having to act as unpaid tax collectors, benefit administrators, checking the residence status of foreign employees etc, and would do anything to avoid falling foul of the nightmare that is employment law.
Witness the number of firms now in business simply to help small employers comply with all the regulations.
Being quizzed by chemist's assistant in Boots.
To think that London, or anywhere else for that matter, does not belong to any one demographic