Statistically speaking, you're wrong; class mobility in Western Europe is equal to or better than in the US.
Good thing you found a country where the culture might have helped you do things you didn't feel like doing back home, but don talk about it as though your personal experience is universal to all, because the numbers tell otherwise.
The issue with most of the studies that say this is how they measure mobility. If the focus is on the ability to move up in income percentiles, then it's an unfair comparison.
Why? Because while it sounds nice to say "avg german child moves from top 50% to top 65% while avg american only moves from top 50% to top 55%", American salaries are much higher, and cost of housing is on par or lower than Europe, so top 55% is a much higher financial increase for the American.
Now that you say it, I see a lot of these comparisons talking about odds of a person born in one quartile/quintile ending up in a different bucket as an adult. Often, it's specifically cited as the chance of a person moving between the highest and lowest buckets. Which on reflection is actually a composite measure of income variability, inequality, and societal wealth.
Running those stats alongside a Gini coefficient would help somewhat, since lower coefficients imply more similar gaps between adjacent buckets. But even that's not enough on several levels. It wouldn't distinguish where inequality falls, particularly patterns like the US and Singapore with large variation inside the outer buckets, so a Lorenz curve would be more useful. It also doesn't clarify the raw size of the changes - position in society matters, but it also matters whether a ten-percentile jump is a 10% gain in purchasing power or a 100% gain.
I'm a bit embarrassed, really. That's a massive gap in the utility of those stats, and I never even considered how many different things the same numbers could mean.
It's something I didn't realize until recently myself. There are several things Europe does better than the US in, but earning power is not one of them.
> If only people had free mobility...maybe everybody could just love in a place that works for them
It would be nice to have free mobility + something like a low-level UBI, for people who really need to be helped and not fall through the cracks. A rather low UBI that focused on just ensuring the basic necessities of life would most likely be quite affordable (e.g. in terms of overall tax burden, or fraction of GDP), and probably wouldn't even be perceived as "socialism". Then we'd probably see places like Europe lose a lot of their former attractiveness as they'd be left trying to manage their unwieldly, dinosaur-socialist states, as anyone with even the tiniest shred of ambition and initiative left would immediately flee for the more open parts of the world.
Good thing you found a country where the culture might have helped you do things you didn't feel like doing back home, but don talk about it as though your personal experience is universal to all, because the numbers tell otherwise.