If your data is worth nothing, then ECC isn't worth the expense.
That's part of the difference between more enterprise level and consumer level equipment. I do some work on my home computer, but I don't have ECC in it. I probably push a few terabytes of work related information over it a year. The rest is many more terabytes of movies and music, and other things that will never notice a bit error. At work where I move 10s of terabytes of information a day, and that information may have cost many hundreds of manhours to create, I use enterprise level memory, disks, and other parts.
I've seen both servers and desktops develop bad ram. You want to know what the difference is when it happens? I get MCE logs from the server and we replace the equipment before anything bad happens. When it happens on the desktop you can end up with crashing programs, reboots, and even worse, corrupt data written to disk.
Again, I don't know how many people out there buy other products with a nearly 1 in 10 chance of undetectably not performing the function they are supposed to perform, but it seems nutty to me.
Although that line of thought does go some way towards explaining the vitamin business...
I personally consider it pretty disingenuous to call a fault that damages data on disk 'transient'. The root cause may have been transient, but the damage doesn't go away if/when a stuck bit functions normally again. Or do you consider a stroke leading to paralysis a transient injury?
I'd also like to see a cite that "most people actually are comfortable with the idea that..." a 'transient' fault that scrambles random data they've chosen to keep. Where, exactly, are you getting this?
Finally, assuming you have some actual basis for that claim, how many of those people run ZFS? You wouldn't conflate nontechnical people who buy the cheapest box at Best Buy with folks who take the time to configure software RAID across several disks using a nonstandard filesystem, would you?
If by your own citation 92% of DIMMs operate with zero errors per year, and a consumer machine has at most four DIMMs, then it is actually pretty likely that any given consumer machine will operate without RAM errors even without ECC. And when you multiply by the low probability that a DRAM error will cause catastrophic data loss, then it is very easy to come to a reasonable conclusion that ECC is not worth the expense.