Yeah, bitpay only need the process to start and then they approve your transaction, I think every system should have to work like that as the transactions of bitcoin once made are unable to reverse,so they should not have to remain in wait their customers until the bitcoin technology is made more advanced.
Yeah, the transaction of bitcoin is not reversible so in that case it is not need to wait for the confirmations, the sellers have to sell the product once they find that the payment has been released from the buyer's wallet, with that we will make the process of dealing with bitcoin more faster , then there will be no any issue of confirmation with any purchase.
The only problem is transactions are irreversible only after included to the block, eg after you get at least one confirmation. Thats why its tricky to use unconfirmed transactions, as you can sign as many different transactions as you like with the same bitcoin you own, but only one such transaction can be included to the blockchain, ever. So good work from bitpay how they can accept unconfirmed transactions to finalize the order process, if it really still works this way.