How do you know for sure that the stick they send you is a valid restore snapshot? Do you have a program you wrote to go verify the contents of each and every

How do you know for sure that the stick they send you is a valid restore snapshot? Do you have a program you wrote to go verify the contents of each and every file on the stick and compare that to what is currently on your system? It seems to me that the backup validation process also has to be provided by the vendor that created the backup software itself. Only they know their file formats. Only they know how to properly compare file A and file B to see if they are correct and accurate.