Most industries using call centers as their primary contact are indeed captive markets where they know they can get away with it.

In the vast majority of consumer-facing sectors, non-captive markets only exist in the pages of introductory economics textbooks.

Even in B2B, most commercial transactions are with an oligopoly, or monopsony, as one party to the transaction. Competition-driven customer service doesn't exist here. For instance, not even enterprise-level customers can get meaningful customer service out of the likes of Google.