Is not about distances, is about the amount of time you have to waste in order to cover those distances.
I'm from a town close to Carvajal's and spent some months studying in Gijon (where Sporting play). You have 3 ways of transport between those zones. The first is your personal vehicle in a 3 hour traject (now, until 7 years ago it was a 5/6 hours drive), I don't think the highways in Germany get filled of football fans with their personal car to watch a game, the logical way would be a train, but between Coruña/Gijon the only direct train that covers that distances takes 9 hours (triple the time you spend if you take a car on your own) and it only would gets worse if you lived between Coruña and Portugal having to come up here for the hub, the last way is taking a four and a half hour bus drive but they're scarce and obviusly if the game starts too early/too late either you'll miss the game or you won't have a bus back home.
The best solution would be travel plans done by the fans to hire some buses and go support their teams, but that's also harder because for example in our region (Galicia) the population density is 4x lower than the Spanish average, and the Spanish average is already much lower than the rest of the German/English or even French average. Beyond the bigger cities (that usually support the local teams) every city/town is smaller than the ones you might me comparing to us and are way worse connected to other places. Even if there was a tradition of traveling with Deportivo for example, probably half the people that would go to those travels would need to take his car, drive almost an hour, find free parking (not easy) and meet somewhere to take the bus they hired with the rest of the fans.
If after all those problems you still have to pay the most expensive tickets in Europe for a Getafe - Deportivo then it's just logical that you'd rather stay in your city to save some money while helping your local economy watching the game with some beers in a local bar