Unless you treat the entire thing as flex time. You need to work 24 hours in the week, not necessarily M-W. Some weeks you may need to work Thursday because of a client meeting. Flexible goes both ways, for the employer and employee. I don’t see the difficulty.
As for other benefits, HC, 401K, vacation, etc., I don’t see a problem there either. You get proportionally less. We have these things called computers that can automatically calculate the bottom line, for the employer and employee.
The biggest hurdle is stated in the OP, cultural norms, especially in merka. One upping each others on hours/week is a national pastime here. Quite sad in reality. Seems the measure of a person is the amount of crap they have.