Not income tax, payroll tax, the tax the employer pays for having employees. Most people are not even aware of this existing. It the one marked “Employer” in this table:
It's fairly cold comfort to know that your employer is paying some taxes associated with your position that don't come out of your notional pre-tax salary.
What most people are interested in is how much of their pay is take-home pay. In the US, the take-home fraction of your pay will typically be somewhat higher. It's certainly not the case that software engineers in the US are getting bigger notional salaries but then paying a larger fraction in paycheck deductions than their European counterparts.
In Germany the company share of social insurance is another ~20% on top of the employees pre-tax salary.
It is not nearly enough to explain the wage disparity between SF/US and European salaries.