user-understandable clock/date weekday numbers?

I love xfce4-panel clock as is very customizable, however I noticed if you want custom format date for places week starts Sunday, it's called day 0, which makes no sense for almost all users--only programmers--though I've been programming since 1993, I never think of 'day zero' rather than 'day one' to the week... can't we have that option for Sunday? There are probably more calendars starting different days, so maybe the week fields should be more customizable?