Free to play with others?

On the xbox they require you to spend money for the game pass in order to play with friends or even other individuals on the SAME xbox. But the same company will allow you to play with friends and local coop on Fortnite? So why not allow all games with a huge mass following or highly sought after to also be free to play with others? Its like they have to make money on top of the companies games they put in the xbox store.