I suppose it depends on the business. It sounds like you were in retail, but I'm in commercial electronics. My last two invoices were around $125k, and CC processing fees on that would cost me $3000 - $4000 per invoice, while also opening me up to battle with a CC company if any customer ever wants to later claim damages. Much safer and less costly for me to just accept payment by ACH or check.I had a business for many years and I cannot understand the "add 3% c.c., cash discount" reasoning.
Most businesses seem to prefer ACH on anything over maybe $30k anyway, as even most business CC's have associated limits, and printing paper checks comes with serious security issues.