Professionals need to be compensated for expenses, even if we don't provide services. Everyone, except you, clearly benefited from your time and expertise. Rates are displayed for burgers. Customers understand if they purchase a hamburger with cheese, there's an extra charge. Fees differ according to requests with each burger.
People go to restaurants and complain about food after they've eaten, then refuse to pay.
Others refuse to pay the full amount. We know there are people committed to not paying for services. CART providers will discover there are people desiring to comply with equal access. Many know little about the law. Many are committed to saving their money or request services without clearing it.