If you go to Wal Mart and buy produce you have no idea how it's created. Many, many hands in the process. Huge batches.
In an Amish situation it's a small deal where everyone who buys from them understand the process, and what they are buying.
Would I trust milk without any inspection at Wal Mart? No.
Would I trust drinking milk that had just been produced? Yes. I did many times. (and I really didn't care for it as a kid).
So you know the name of the person who picked your onion if you buy from the Amish? Doubtful.