Because, as the kids say, we live in a society.
Of course there are individuals who prefer working Sundays or nights but of you implement these policies on a society level most people doing these jobs will be forced into them and won’t have any significant free time overlap with their families and friends. If you haven’t lived it, it’s hard to describe how nice it is to have a day each week where the expectation is that everyone in your country is having time off at the same time (with exceptions of course, such as emergency services, but also the people catering to the strolling masses, i.e. those working in cafés, museums, etc.)
