Finland is nearly as bad. 20 years ago there were only 3 food chains. All domestic and playing the rules "no price competition". So food prices were about 30% higher than in Germany for example (these a very different countries so lack of competition is only one reason). Then Lidl (discounter of German origin) entered the market. The first years the incumbents fought it with unfair practices, but in the end it led to more price competition with everybody having to offer cheaper choices. 2 of the incumbents have since merged (with some regulatory limitations) so we are back to 3 players, 2 playing "according to the oligopoly book" and one doing things different, at least offering some choice.

Banks are not much better. There are a couple of small players additionally to the 3 big ones, but competition is limited to very few products. If you are interested in something else, choices are very poor.