There is a term called “spontaneous collusion” that addresses this. Basically, so few firms compete in this space (the barrier to entry is high) that it is an oligopoly. They legally can’t collude, but they do. They don’t really want to compete on price, so they don’t. A good example of this is Coke vs. Pepsi. Both are sugar water and they make buckets of cash selling a can that is 4 cents to make for 70 cents. They don’t compete on price. They have colluded to come up with a fixed price for their product and they use advertising to gain market share. Safeway Select is 25 cents per can. It is the same stuff.