I think most big-L libs fail to take into account a couple of obvious things about human nature. A) People are stupid and B) people are sheep. The idea that the market will select the best price is only true if people are intelligently able to figure out which price is the best one. And as you've said, lotsa companies go a long way out of their way to obscure the real price of their good or service. The first big downfall of lassiez-faire economics is that a real free market requires that all consumers have (near-)perfect information about cost and availability of just about every good almost all the time. But this assumption is almost never true in the real world.

The obnoxious dogma that's continually spouted by the free-marketers on this issue is one of the big reasons I don't claim to be a big-L lib.