I can understand that argument.

But conversely if everyone is forced to take the same day, or days, then it entirely ignores the idea of different cultures.

In Islam their...... (sorry -- can't think of a better way to phrase this) their Sunday is Friday. So it is most likely that in a Muslim family most of them would want their rest day to be Friday.

Christians would take Sunday. The Jewish day of rest is Saturday.

Yeah -- there'd be allowances for schools, and teachers in state/secular schools.

I understand the friends problem, and it's something to work around, but as I said if you force every culture and every person into taking the same day just because one culture or one religion says "this is the day" then....... it seems somewhat dictatorial.