Public sector pays less, and from experience that means that if you are in London you live quite a frugal lifestyle.
Yes London lawyers and bankers can earn a lot more, even new graduates. To some extent there is a trade off between money and job satisfaction. I would argue, from observation, that senior doctors in their fifties can have fantastic careers, whilst many bankers, from their early forties onwards are looking over their shoulders worrying about redundancy and their places being taken by a new generation. Plus after some hard graft in a London teaching hospital, many doctors with young families will choose to start applying for consultancy jobs in cheaper and perhaps more congenial parts of the country. Options not available to many city bankers and lawyers.
Those high salaries can be addictive and spending can be a substitute for job satisfaction. Though living in central London, we were never able to keep up, no weekly cleaner for us, nor anything but family hand me down cars, and cheap gite holidays. (And lots of good stuff, like free museums, last minute theatre tickets, brilliant parks etc.) Seeing people for whom the high earning days came to an abrupt halt, we don't regret our inability to live it large.
Alreadytaken, I wonder if this is a more acute problem for Oxbridge grads. London medics will be well practised in frugality, whilst I see no evidence of DDs non-medic friends aiming their sights on law or banking. Teaching or the civil service would seem more likely. Her friends don't seem particularly interested in either earning or spending a lot, plus outside Oxbridge/London it is harder to land this type of job.