Comment by sfink

Yes. That is what "...unless the base rate is set externally somehow" means.

It is different initially, when only one company is offering the "discount" and they have not yet adjusted their base price upward. In fact, the people who want the discount will presumably flock to their service, which may even mean they won't raise the base price all the way up if it makes their costs lower. But if that works, the other companies will follow suit.

In short: there's a period of time when there's a difference, and you have a real choice. If the difference is real, it will get locked in to the entire industry. It's a positive economic profit, and those go away.

cf https://robert.ocallahan.org/2014/08/choose-firefox-now-or-l...