We had roaming charges in the past but not anymore in the European Union (and Switzerland, Norway, Iceland and Faroe Islands) I can go to Germany, Italy, Denmark call and use internet like in Barcelona, no extra price. The European Parliament has been pushing providers to remove roaming within the EU, and this summer is happening already, not all companies but many, by next June will be mandatory to all of them.
So, your point is not valid anymore
Source: Europa https://ec.europa.eu/digital-single-market/en/roaming-tariffs
Awfully smug… Wait to you see what happens to the prices after they have to allow people to do that. Just Because a couple carriers have started to do it doesn't mean that the full costs are factored into those plans yet.
Also consider that Europeans are far less likely to travel across the continent then Americans are. Despite the often repeated line that many Americans don't have a passport, I would bet a lot of money that we traveled much more in terms of miles during a given year for vacations and the like.