AFAIK, that's never happened because WM got a photoID from a money order purchaser. OTOH, those who purchase money orders without ID are much more likely to be reported. One reason to file a WM SAR is that the customer refused to provide photo ID. Your choice.
A Walmart-filed SAR without any photo ID-related information on file with UST is an intense problem for the attempting MO-buyer who didn't buy the MO? Are WM clerks reporting J. Doe to UST/FinCEN for a suspicious activity that didn't take place and saying it was done by some unknown person?
A SAR filed by some company employee who accepted and processed SARs with stolen/fraudulently-used real photo ID is is a more intense problem for a real person hit with a series of SARs based on fraudulently-used ID for questionable MO purchases than it is for a real person not hit with a series of SARs because their photo ID and name was never captured and never ended up available for misuse for questionable MO purchases or other activity.
Not trusting a retailer and their low-paid employees with protecting ID documents and their data is suspicious? Only in the world of suspect thinking at this point ... in a world where many innocent people have had problems with the UST/IRS because of misused ID being used to report income and activity that was not their own.