I agree with what you are saying, but you are in essence asking someone to develop and maintain a service, but not get paid for it. Whenever a service is provided, some sort of fee is typically going to have to be paid.
Service? I was talking about something the merchant can implement. A piece of software so that they wouldn't have to use Bitpay/Coinbase and could interact direct with the exchange. The merchant runs this themselves accepting BTC directly, and they'll save the Coinbase/Bitpay fees and not have to depend on them.