The biggest misconception is that America could have a European welfare state if we just taxed the rich. The reality is the rich in America only pay slightly lower taxes than their European counterparts.
In Germany top income tax rate is 50%. In the US, it's 37% if you live in Texas and 56% if you live in California. In Germany long-term capital gains is 25%. In the US, it's 24%. In the US the corporate tax rate is 21%. In Germany it's actually lower at 16%.
The primary difference between Germany and the US is not taxes on the wealthy. It's that the German middle class pays significantly more than the American middle class. A couple with two children, each earning $65k/year will pay 28% of their income in taxes. Then on top of that they'll pay 19% in VAT tax on nearly every purchase. Effectively for every Euro earned, they're left with post-tax purchasing power of 59 cents.
In contrast, the same family in America will only pay 11% of their income in taxes. Depending on state sales tax comes in at 7%, and unlike VAT at most applies to maybe half their budget. For every $1 of income, this American household is left with 85 cents of post-tax purchasing power.
And that's the main difference right there. European welfare states are powered by taxes on the middle and upper-middle that are simply unacceptable to the average American voter. Imagine a politician running on a policy of tripling middle class taxes. It doesn't matter how much single-payer healthcare, free university education, and expanded public transit they promised. Americans would simply never vote for that.