If many retireed at 60 in the UK they would be on income support, surely as many pensions dont start till 65?
Sometimes companies need people to stay on longer in all levels of the firm if the person is willing its better they stay. Seen many a firm have to bring in somebody back as a consultant as they for whatever reason (either the employer didn't request them to pass on skills or knowledge, or the employee kept it to themselves to protect themself from being booted out early)
Very rarely ever seen or heard of a company reducing hours and increasing staff in the private sector.
Of course its common in the public sector but efficency is never a big issue. Many times my company finds oursleves having to deal with two sometimes three people who work in the same postion as they job share. These projects big or small always take far long to complete and normally never to the complete satisfaction of both parties.
Strangely I was told by a HR bod that often the job share employees were paid far more than a indivual worker and of course the employers costs were far higher.