> Not all corruption is detectable.

Well, I don't know rsync that well. If you're saying it doesn't detect changes to files while it's being copied, then I'll believe you.

And, as far as I know, it's impossible to detect absolutely all corruption.

But you can pretty easily detect, e.g., that a file has or has not changed since before you copied it to after, on a system with a basically functioning filesystem and clock, with a reasonable/useful level of confidence.