n.b. Developer salaries are considerably lower in London than in many parts of the US. (Although that's still low for a senior role). Aside from banks, not many places will offer £40k for an entry level graduate role.
Have you ever been outside of the bay area? Go someplace not in the top 3 for most expensive real estate and you'll see kids 3 weeks out of school making $40k a year with plenty left over after paying for their car and 1-bedroom with no roommate.
God it's like everybody on HN was born and raised in SF and has never made less than $150k a year.
Well, I was born and raised in SF, but have interned in Seattle and Austin. I'll be the first to admit money goes further there, but even in those places my full time offers - years ago - exceeded $61k/year.
$60k seems low for me anywhere for this reason: Even with the Bay Area's high cost of living, a college hire with a $90k offer without a family who wants to live with roommates will be able to save more than someone in a low cost of living place making $60k. The $20k additional take home will more than cover the added cost of of a room (perhaps $12k more/year).
As far as one bedrooms go, at $60k you can find one bedrooms for $1600/month or less in SF (less hot places or below market rates in hot places). In cheap Austin, $600 is about the minimum. That's a $12k a year spread, but not enough to not take a $60k SF offer over $40k in Austin.