As they say, "don't hate the player, hate the game", in this case the "game" being Google.
Unless you are a very large "whitelisted" brand, it would be irresponsible, at the least, to interlink your websites. If you have 3 websites on page 1 and you interlink them - there is at least 50-50 chance you'd get slapped with a penalty on all of them. At those odds, I can't blame anyone for trying to keep their websites as far apart as possible.
Now, how they decide to do business with their visitors, that's their business. Unless legally obligated, they can do whatever they want. If you think you can do better - there is no barrier for you to build 2 more websites and rank them along your main website, or 5 or 10.