Willing?

Worked an easy shift with one job in 12 hours. In fact we had a patient with us for exactly 1.7 miles.

Heading in for the day I said to my partner well we kept the work to pay ratio at a good level. I then further commented hey we're payed to be available and we were.

He came back with we're not paid for what we are available to do, but what we are willing to do. Like for instance standing in a snowy ditch holding in someone's guts etc.

So what do you get paid for? Is it skills, availability, willingness or something else?