It's possible that he is running one compact and one standard crank but you'd think he mention that. He did mention that he has one bike which works perfectly as designed (no rub in any combination) and one, ironically with higher spec components, that does not. Either SRAM really truly does suck at front derailleurs, or shop B is the real problem.

I can't disagree that knowing how to tune one's own derailleurs is a very useful skill but some people simply have zero interest in doing so. If I had paid a shop the money for a SRAM Red 11 speed bike, I would expect at least enough effort from them to get my front derailleur working properly.