Please Use ZFS with ECC Memory (2014)

Back in the distant past (1980s-1990s) we used to say only ECC memory because once you got much above 128Mb of memory, the risk of an unexpected bitshift was too high. We were talking Sun workstations and like rackmounts. Mainly. PC's were still not entirely taken seriously as servers.

I think if, at that time, the industry had shifted to ECC only, we'd have been fine. The thing is, the industry recognized this as a price differentiation point, and although its really been absorbed in VLSI real estate and complexity by now, it was seen as "too expensive"

TL;DR why is ECC still seen as a price differential on plan RAM, when its just lost in noise in the BoM for the silicon? Why isn't ALL ram ECC ram?