>More likely, by issuing the refund via debit card, Wirecard and Verizon are able to extract every last possible penny by way of debit card fees and people who simply didn't bother to get their money off the debit card, by virtue of the friction they created for the customer with the debit card.

In my experience you don't get charged fees if you try to spend the money normally (eg. at a store). There's still the problem of spending every last cent on the card, but supermarkets and gas stations generally allow charging an arbitrary amount to a debit/credit card. I think they even have a free option to transfer the balance to your bank via ACH.