For such small amounts, I am surprised Amex ruled against you on the disputes. Many credit card issuers (not necessarily Amex) often just issue credits without any investigation unless you dispute charges often or the disputed charges are higher dollar amounts.
LAX
Yeah this is definitely not the norm for AmEx. The rare 1-2 times I've disputed a sub ~$25 amount, AmEx instantly
Closed the dispute in my favor. I assume it's an auto-process depending on the dollar amount being disputed.