You might be interested to know that in Israel the work week starts on Sunday, not Monday. Friday and Saturday are the weekend.
That might just be a factoid, except that the Jewish Sabbath was the origin of the weekend concept. It changed in countries with a strong Christian influence so that Monday because the first day.
It never changed in the US because the Jewish workweek had a stronger influence there than the Christian one.
> I personally detest calendars which display Sunday as the first day of the week
And I personally find calendars that start on Monday quite bizarre since it's obviously incorrect historically.