Upward mobility is higher in Denmark, where I'm from, so that's what I'm familiar with. I don't think this metric necessarily measures exactly what people expect: The spread of possible outcomes is simply much tighter. Making $65,000/year puts you in the top 10% of earners, while the bottom 10% ends at $19,600/year. When tripling your salary is enough to travel almost the entire scale, obviously more people will do it. The same numbers for the US are $150,000 and $6,560 (not adjusted for purchasing parity or tax, so grain of salt). Or put differently, the 10%-90% income range for Denmark fits inside the 25%-75% income range for the US.
We have a lot fewer poor people in Denmark, and that's undoubtedly a very good thing. But there are also very, very few people who would be considered more than comfortably middle class in the US.
I don't know a good way to measure this, but I think that you can move further, faster upwards in absolute numbers in the US rather than in Denmark. I would expect that it's comparatively easier to for someone born around the 20%-mark to make it to 80% in the US than for someone to make it from 10% to 90% in Denmark, even though about the same journey in absolute numbers.
If I recall right, the mobility was measured by percentage of people who move out of their bracket. E.g. US kid born into 20% bracket is more likely to stay in that bracket. If you move, you make bigger jump (cause differences are bigger), but you are unlikely to move.
We have a lot fewer poor people in Denmark, and that's undoubtedly a very good thing. But there are also very, very few people who would be considered more than comfortably middle class in the US.
I don't know a good way to measure this, but I think that you can move further, faster upwards in absolute numbers in the US rather than in Denmark. I would expect that it's comparatively easier to for someone born around the 20%-mark to make it to 80% in the US than for someone to make it from 10% to 90% in Denmark, even though about the same journey in absolute numbers.
https://dqydj.com/united-states-income-brackets-percentiles/
http://www.statistikbanken.dk/statbank5a/SelectVarVal/Define... (Danish)