>>>I am surprised that anyone still thinks about Sunday as being the start of the week<<<

Certainly it has quite a bit to do with the calendar. Sunday is always the first day, unless, as mentioned, the calendar lumps the 'weekend' into one section. Sunday being the start and Saturday the end appeals to me for another reason as well. Wednesday is the middle of the week. If Sunday were last then the week would be very unbalanced.

In addition, in every job I've ever had, the pay period either ended on Friday or Saturday. My most recent job ended its pay period on Saturday, so the week definitely began on Sunday. In previous jobs where the pay period ended on Friday, one could say that the week began on Saturday.