Wrote an article for a company. They paid me but have since ghosted me. Why do companies expect proper notice and loyalty again?

This company was jazzed that I write for them. I did a really good job and they paid me. But now…. Crickets. If a contractor or employee did that to a company, it would be seen as utterly unprofessional. Serious question: Why are they allowed to treat us with such indifference and unprofessionalism and get away with it?