Well, it seems clear that the market was failing to deal with this adequately. Three has had free roaming for years, correct—it wasn't across the whole EU thoug

Well, it seems clear that the market was failing to deal with this adequately. Three has had free roaming for years, correct—it wasn't across the whole EU though, worth remembering!—but the market had not efficiently reduced the costs for everybody. You could certainly make the argument that there were other reasons that people didn't all switch to Three, but it seems more likely to me that people consider switching to be too much work. That's essentially an inefficiency in the market – exactly the sort of situation where a regulator should step in. After all, roaming charges in the EU were essentially price-gouging of the worst kind.