Most of the RAM may not be critical enough to crash the whole system. Just some random app you have open or a browser tab. So even if it is true, most bit flips should not crash a system.

Servers with ECC generally report zero recoverable memory errors until the chip starts failing, at which point there are increasingly many. Therefore the average server experiences zero cosmic ray related memory errors during its lifetime, despite having many times more memory than 256MB.

How many of those errors vould result in a full system crash, though? And how many of them are just going to cause silent and mostly-harmless data corruption?

After all, was the error in the first line a typo on my side, or a single-bit upset?

A while ago some researchers registered off-by-one-bit domain name typos, which due to physical key positioning were unlikely to be the result of genuine mistyping. I can't find a reference right now, but I recall them getting quite a lot of queries!

It's not true.

I have left memtest86+ running on a few dozen GB of memory for several days during burn-in testing, definitely more than enough to pass the "once per 256MB per month" threshold, and did not encounter any errors.

Write a Bit Flip simulator and report your observations ;)