"The problem with this is that it assumes either a monopolistic seller or explicit or implicit collusion between sellers. Because if the market has vigorous competition then engaging in price discrimination will only drive the customers being discriminated against to your competitors."
That's why gp used a movie theater as an example. The movie market depends on state authorized monopoly in the form of copyright. The result is that price discrimination is more legitimate and more beneficial to producers and consumers than it would be in a competitive market.
Of course, copyright exists as a trade off. The benefits of promoting the arts are worth it even though monopoly is bad, as long as the system is administered reasonably and competition exists between different producers of copyrighted works and each has a monopoly only on his own product.
The economics of a complex trade off like that are not a guide to how other open markets should work.
And even well intentioned state monopolies can be run badly and become a disaster. Just look at software patents.
That's why gp used a movie theater as an example. The movie market depends on state authorized monopoly in the form of copyright. The result is that price discrimination is more legitimate and more beneficial to producers and consumers than it would be in a competitive market.
Of course, copyright exists as a trade off. The benefits of promoting the arts are worth it even though monopoly is bad, as long as the system is administered reasonably and competition exists between different producers of copyrighted works and each has a monopoly only on his own product.
The economics of a complex trade off like that are not a guide to how other open markets should work.
And even well intentioned state monopolies can be run badly and become a disaster. Just look at software patents.