Sometimes companies will make more money by refusing to give consumers what they want. Collusion is also extremely profitable. A competitor that isn't interested in playing along can be bought out, but once shareholders get involved they're going to insist on screwing over their customers just like everyone else does anyway because they'd be leaving a huge pile of cash on the table otherwise and short term profits are all shareholders care about.

"by refusing to give consumers what they want." in practice consumers don't really want that, that much. The companies do similar things due to the similar ways consumers react to them. That's the point of this rely chain.