Distance is a factor. But another one is that trads often have only religion in common. In my experience, that isn't enough to base a friendship on.
I see I'm not the only one that realizes this.
I mean, you have suburban or "yuppie" culture families (starbucks, don't use car seats after they "expire", home in the suburbs, order in pizza on Friday night, don't own a gun because they're "dangerous", and in general do everything the way "most people" do) and rednecks (live on land, have livestock, boys often go shirt-free and pee in the yard, hunting and shooting practice, and in general live a much more down to earth lifestyle) and lots of things in between.
You have sports nuts, construction workers, computer guys, and those who argue for or against BoD as their main hobby. Quite a variety there!
Just like in High School, you have jocks and nerds. And the jocks tend to have jocks for children, and the nerds tend to have nerds for children. So the children have the same issues forming friendships. Some boys like to play sports, climb trees, and roughhouse outside. Others like to build with Lego, read novel after novel, play exotic musical instruments, and/or write computer programs.
And let's not understate what a night-and-day difference in lifestyle some things cause:
homeschool vs. sending kids to public school
grown kids vs. having a bunch of little ones at home
no kids or unmarried vs. having a bunch of little ones at home
rich vs. poor
city vs. country* (as long as your lifestyle matches where you live)
Except for being at the same place every Sunday morning, I don't see a lot of similarities among some of the parishioners.
(* I probably grew more stuff when I lived in the city than I do now in the country. Likewise, some rural dwellers live exactly like city folk. So what really matters is lifestyle, not geographic location.)