I’ve been orbiting the sun for more than 40 years and that’s the first time I’ve heard that

It’s because it’s not true. It was always “the customer is always right”, full stop, originating in 1920s department stores as a slogan to encourage employees to be doormats for entitled customers. Gotta make the owners richer at the cost of the employee’s self respect. Then folks on the internet uncritically started repeating this “matters of taste” nonsense in the last decade or so, and here we are.