You are a bit naive here. Those type customers are extremely common, and there are specialized jobs to deal with such customers.

In SW they are the PM's. Without a good PM to shield you from the customers insanities you are lost. In architecture or other engineering professions it's the same. As architect you have a special man to deal with politicians and special clients, and in many other professions even with the press, who has no idea either.

Never talk directly to the customer. Or if so, you are not allowed to make promises.