Why do restaurant cooks insist on getting off at their scheduled time?

In any other industry, once your end time comes, you finish any further work you have and then clock out. But cooks are like, "Nah, I'm not serving you because I get off in 5 minutes." Why?

I used to work at a restaurant. Even though I wasn't a cook, customers had all of my time and attention until I was done serving them.