People will pay more for priority service, even when they know other firms will do it cheaper.
It's a fact of life for service contractors who know what they're doing to get complaints about their higher-than-the-going-rate prices. Most of the time, these complaints don't start with the customer. In most cases, the customer is egged on to complain after talking to some plumber who doesn't know his cost of doing business and tells the customer he would have done the work for half the price.
This has become a serious problem for many flat rate companies around the country. Some have been harassed by consumer protection agencies that believe the "going rate" is what everyone should charge. No matter how many cost breakdowns and P&L statements you show them, most of the people who work for those agencies have never run a business. They can make life miserable for a knowledgeable service contractor who tries to do right by his employees and operate profitably.