No. This is a saying that is incorrect. A more realistic saying would be the customer is always right within reason. Some consumers are really unreasonable in their demands. I managed restaurants for twenty years, worked in call centers for 10. And I have encountered all sorts of people. One person in my call center days had said his HD cable tv services stopped working and when I checked his account, I found he never had HD services on his account. The guy spend an hour with me on the phone yelling that he had HD and wanted it fixed, when I offered to put HD services on the account to Fix his problem he didn't want to pay for them. I even proved that his cable box was a regular Digital TV box, not HD. Another customer in my restaurant management was a woman who ordered the smallest order of fries. She then wanted enough ketchup packets to fill a large ketchup bottle. When I told her max 4 packets she flipped out and caused a scene. (PS: anymore than four packets would have eliminated any profit made from the small fry). Another story I have is when I briefly managed a retail store, a customer wanted her money back for a soap dish, toothbrush holder and soap dispensor because she claimed the one piece was broken. Yet when she showed me the receipt she had bough the items six months before and they were all disgustingly dirty and grimy and even had mold growing on them. Another one is a customer went into my bf's clothing store and demanded his money back for some underwear he purchased. The underwear had skid marks and pee stains. When he said no, he couldn't take them back by law, the customer freaked and caused a scene.
Customers can and will be unreasonable. Many will try to scam the store. So as a result stores have strict policies. So no, the customer is not always right. Now as for the costs. One of the biggest costs for a business is labor costs. In retail and hospitality, the industry standard for labor costs is 21 percent of your sales coming in. Labor is also the biggest cost for companies. So lets say you have a min wage of 10 bucks. And you have to have a min of 2 employees in a store. You need to make at least a 100 bucks an hour to be able to pay those two employees. Now where I am we recently raise min wage and it will be 15 bucks next january. That means I have to make now 300 dollars in an hour to keep my 20 percent labor cost or I will lose money. The alternative is to lay off one employee. However many business' cannot do this for many reasons, some are safety, insurance, and even operational reasons. So there is no choice at that point to raise prices. If min wage increases every year or every few years then prices go up to compensate in order to pay those employees. The more employees a company has the more money they have to make.