How much taxes do Americans think we Europeans pay? Those dutch parents are paying close to 60-70% taxes once you account also for VAT
Not to mention the myriad other ways to defer or exempt future income from taxes such as 401k/IRA/roth/529/HSA/etc.
And then on top of that, you have 50 different states with myriad ways of taxing income, different types of income, consumption, and estates, and within those 50 states, there are numerous counties and cities with their own ways of taxing the same.
For example, my effective individual tax rate at similar W2 incomes has varied from 30% to 17% (including health insurance premiums) just by changing the jurisdiction I live in. And that’s calculated using various assumptions one may or may not agree with.
I'm pretty sure the Netherlands has payroll taxes (employer paid) as well, so you would have to balance that assessment with what employers are paying.