A US senior software engineer making that much would live in a major tech center and would probably work for a very good company, so a lot of people are excluded because of location and others just because of selection. It's hard to say, but I can't imagine more than 30-50% of US senior software engineer making that much.
And for Germany, the salary for a senior software engineer is not that low :-)) A senior software engineer in Romania or Ukraine would be making that much (while living in less developed countries with much lower cost of living). The only way their salary would be so low in Germany would be if they would be working for a crap company in a small city.
So you're not comparing apples to apples.
However the general point can be right as I'd say that the correct number for the us would be more around $150k and the correct number for Germany would be around $90k. So you'd still have a $60k gap.