> but I can bet no one is too happy about it when a breach of contract happens.

It's very odd that you consider this a breach of contract, because these contracts are pretty heavily policed by regulators and the courts. Check every ticket you've bought, the contract of carriage includes terms specifically about overbooking.

For instance, here's United's Rule 4G:

All of UA’s flights are subject to overbooking which could result in UA’s inability to provide previously confirmed reserved space for a given flight or for the class of service reserved. In that event, UA’s obligation to the Passenger is governed by Rule 25.