Process enough data and even ECC can - and will - fail undetected. Any kind of mechanism you come up with is going to have some rate of undetected errors.
Given the rate required for this its not a reasonable assumption. It's like saying Amazon sees sha256 collisions between S3 buckets. Just doesn't happen in practice.
Undetected ECC errors are common enough to see from time to time in the wild. This paper estimates that a supercomputer sees one undetected error per day.
