Not so enormous for me, but then I live and work in Switzerland, which is the country with most probably the highest cost of living in the world (besides cities like London).
On the other hand, if you factor in the totally missing social security system in the US, and the crap work contracts you get there, a higher income is actually just making up for the difference in benefits.
(like 2 weeks of notice if you are fired... its 3 months here in switzerland most of the time, depending on your contract and the amount of years working for a company, could easely be around 6 months, sometimes those are 6 months paid without having to work at your old company anymore, or at least your are allowed to look for a new job on the old companys payroll).
Now, what is skill level 2 exactly? Because I have seen a quite large discrepancy in what a developer, and senior developer can expect being paid.... Senior can get 25-30% more without a problem.
Then this seems to be a national average. Keep in mind that in some areas developers might make a ridicolous amount of money, driving the national average up. Just tick the checkbox and you see what I mean. The fact that the biggest employers for software devs tend to be located in these areas, thus they employ a quite large portion of the develoeprs in the US, of course skews the picture even more.
I would bet if you find a job with a small software development house in Utah or Texas, you can slash at least 25% off that salary, if not more.
EDIT: Oh, do I read "London" in the checkbox description? Is this meant to be a worldwide average? Then I have to question what countries besides the US and UK are included, because I know there are a ton of developers in India and the CIS Region, and they have WAY lower incomes there.