Note that other card processors don't charge the $15 fee. Stripe is a bit different as they are set up as the merchant (rather than the business) so chargebacks hurt them more than the standard merchant / card processor arrangement.

Fully agree with your final sentence though, some card processors rule against the merchant regardless of evidence supplied. It makes the whole process pointless. It's actually simpler to take a customer to small claims court than defend a chargeback, and at least the court will look at the evidence. Such a waste of resources, sadly.