How could this have been profitable? I find myself looking at images of uniformed gas-station attendants in cute caps, cheerfully wiping your windshield. I'm too young to remember those guys, but we've all seen images.
Inflation-adjusted minimum wage was higher back then, so it's not like they worked for free. I'm guessing it's before the advent of "maximizing shareholder value" as the only measure of business success. Back in the last century, businesses had other values as well.