Except those that own Subarus, of course. Their AWD system demands uniform tread thickness. Not sure about any of the other AWD systems.
I will say this t(h)read has been interesting (sic)--I'd always assumed that the best tires would go on front. Are there any tire/car manufacturers advocating the best tires on the rear?
Semi-moot with me, as I've always strived for equal tread all the way around, mostly attainable by rotation. Really not that expensive to do--Ford dealers are advertising an oil change & rotation for about $35 + tax, DIY even cheaper...it's the balancing that gets expensive.