Instead of attacking author Schumann’s arguments, perhaps we ought to cast a fishy eye on the self-satisfied, self-righteous dogma “the customer is always right”.
The latter has been enshrined in American commerce. Combining with the modern tendency toward self-regard and instant gratification, it leads daily to demands (from customers) that service providers violate every law of physics (not to mention legal codes); and it is demanded that they do so in a hurry, for not very much money.
They are, however, always the customer...and the customer is always the point.