You can't do that for people with no impulse control or long term thinking. You saw it as promise broken, but they saw it as someone wanting them to do more work for money they already got and spent.
To tie it in to sports, you see that these days with athletes wanting to renegotiate contracts. They can't comprehend it's fair that they have to get paid less because of a contract they signed than if they were a free agent under no contract.