I have looked over the SCAR rifles in both 223 and 308. Neither one has the same amount of machining as a standard rack-grade AR15
If machining time is the cost driver rather than quality, why are there not SCAR knock-offs undercutting the AR market? It's because machining isn't the most expensive of manufacturing techniques anymore (in fact, the aluminum machining associated with ARs is among the cheapest these days)
A SCAR costs more than an AR because FN guessed correctly that some people will tell everyone how beautiful the Emperors new cloths are, but the Emperor is actually naked.
'Naked' is a bit of exaggeration, would you not say? So, your argument against the SCAR is that it costs less to produce than the AR (which is actually a very good thing let's be honest) but is only sold for more than it's worth because FN are idiots that hate market share despite the gun being developed for mass-issue contracts?
Remington's piston AR is expensive, Bushmaster's is expensive, Magpul's is expensive, Ruger's is expensive, SIG's are expensive, HK's are (very) expensive, FN's are expensive, B&T's are expensive, the conversion kits are expensive... seeing a pattern? Were the concept truly cheap to pull off, why is some clever firm not undercutting all these guys and stealing their business? Because we all know the price is a huge barrier to entry for folks who would otherwise partake.
Going cheap on a piston design gets you the G36, by the way (an excellent design deeply wounded by cost cutting)
It's almost as if the cost to produce & market an autoloading rifle that isn't leveraging the public-domain AR elements in their entirety costs a bit over $1500 any more. Or maybe it's a selection-bias thing, and only higher-end companies with more operating capital for R&D bother developing these projects
There was a time when Mauser bolt actions cost a lot more than rolling block patterns which had served valiantly for fifty-plus years...
TCB