First of all, yes, labor is taxed much higher in Germany than in the US (PPP adjustment already takes VAT on prices into account, so that doesn't matter in this case). In fact, Germany has one of the highest taxations of labor in the world.
What makes this analysis tricky is disposable vs. discretionary income. The US clearly comes out on top when it comes to disposable income (labour is taxed too much in Germany compared to capital income and wealth).
The picture gets more complicated when you look at discretionary income, which also accounts for regular bills, such as rent, college tuition, out of pocket expenses for health care, childcare, and such. All the taxes you pay in Germany do also pay for something, after all. There is unfortunately very little data for this type of comparison.