I've worked shift work with only Fridays off before. It was not tangibly worst than having only Sunday off. In fact I would say it was better because dealing with certain government bureaucracies that close down on Sundays was significantly easier. You can't expect the entirety of society to shut down on Sundays so there's always going to be somebody who has to work during that day.
You may have 2 days off but your friends and family are likely working during the days and in "nothing too exciting" mode in the evenings.
The benefit of everyone having Sunday off means that (for the most part) the rest of the world also has Sunday off and you get to enjoy time off with your friends and family.