I posed this question as well. Quickbooks has no intentions of doing it. I don’t know why either. But ever since they to me to go into the “gear” icon and gave a “work around” for the request of adding in a convenience fee I just turned off the paying by credit card feature off my invoices. I know in 2020 from my business alone quickbooks missed out on thousands of dollars in transaction fees they could have capitalized on. I’ve been giving incentives on Venmo payments.