Many of these lists are not per capita. They ignore that USA has a population roughly half of all Europe (not to mention that it's considerably more diverse in most places).
For example, using the table from a recent The New York Times article, America's Gun Problem of mass shootings (public shootings in which four or more people were killed) from 1998-2019:
Notice that Finland had 3 where USA had 101. However, Finland population is 1/60th of USA. Adjusting per-capita and this statistic seems to show that mass shootings in Finland are relatively (based on population) 74% more frequent than in USA.
Wikipedia considers that there were seven major news-worthy mass shootings in Europe last year. In the same time-span, The Onion reported their headline 4 times.
Wikipedia considers that there were four major news-worthy mass shootings in Europe during 2020. The Onion only got to use their headline one time that year. Adding 2019 to give a three year total makes the score 15 to 8 (Europe).
Using the frequency of The Onion headline occurrence itself as a guideline, then one would have to say that the USA does not actually experience regular mass shootings, but that they do occur, on average, a few times per year. Between 4 August 2019 and 23 March 2021 (more than 18-month period), the headline only found a single opportunity for invocation. (However, on 4 August 2019, it was used twice!)
Some other points for perspective:
The above TNYT article explains:
Most shootings in America never appear in national headlines. The majority of gun deaths in 2021 were suicides. Nearly half were homicides that occurred outside mass shootings; they are more typical acts of violence on streets and in homes (and most involve handguns). Mass shootings were responsible for less than 2 percent of last year’s gun deaths.
That includes suicides which are almost 2/3 of the gun deaths.