Is it fair for a platform to charge commission on cancelled orders?

[chrono18k]

Matt (Support Advisor): I really do not like to be the one to have to inform you of this but we cannot refund or reverse these fees once the order is completed.

17:49 Matt (Support Advisor): I do understand that the order was cancelled. I do see the timeline in the admin.

MY ORDER HAS BEEN CANCELED BY THE BUYER, EVEN THAT SHOPIFY IS CHARGING ME $718.00 OF COMMISSION FOR A CANCELED SALE. THIS AND THEFT