In this case you're trading out your effort for the cash. I'm happy to trade my money, which I earn much more efficiently at my job than I can save by cooking,

In this case you're trading out your effort for the cash. I'm happy to trade my money, which I earn much more efficiently at my job than I can save by cooking, for the food so I don't have to put in effort and can enjoy my evening out with friends. I'm also more than happy to pay a couple of dollar premium to eat fast food than try to recreate it on my own while I'm running to work.