Sweden is a country with the population of New York, but have one (sometimes two) universitites in a global top ten ranking of their respective subjects. So if you must compare to something US, do it with a large city.
Sweden has two universities in the top ~100. Boston has three. New York, Los Angeles, Chicago, Atlanta, San Francisco, and Pittsburgh have two, mostly in the top 50.
That's because your source is coarse grained. Look at a list of specific subjects, in my example medicine (and an old list of maritime biology institutions, hence "sometimes"), and you'll find the counter examples.
But hey, I'm cherrypicking data here, so it's not relevant to anything else than as a counter data point to a very broad and wrong statement.
While this might be true for maybe population size or territory, the govermental structure is completely different. ..also there are huge cultural differences (language; diff. social path dependencies etc.)
I don't think the similarities justify comparing US states to European countries.
No, you shouldn't. European nation states bear little resemblance to federal states, neither historically, culturally or economically.
The point was not that comparisons between states and cities are somehow more valid, but to illustrate that the differences in higher education are most likely due to the vast population difference.
Sweden has two universities in the top ~100. Boston has three. New York, Los Angeles, Chicago, Atlanta, San Francisco, and Pittsburgh have two, mostly in the top 50.