Who started this idea that the customer is always right?

I meet retailers who are so frustrated by that statement.

• There you stand with a customer swearing that the jumper they bought last week was one size but by the tie they got it home and put it on their child the garment had changed size.  You want to tell the customer that it couldn't possibly have happened but you know from the slogan that the customer is always right.  You just can't bring yourself to say how sorry you are for stocking such rubbish.

• How about the situation where you warned the customer not to freeze the garlic bread because it was best eaten fresh but they did it anyway and now they are telling you that you make lousy garlic bread.  You want to tell them they are stupid but then you remember that the customer is always right.  The words stick in your throat and you just can't apologise for being a lousy baker.

• And then there's the day that a customer pops in unannounced and wants their hair done right away declaring that she has an appointment this time every month.  You know she is wrong and yet you know you are supposed to say she is right.  You split in half, dumbfounded at the idea.

And what about a thousand other instances where the customer is just plain outright, clear as day WRONG?  How can you go along with 'the customer is always right'?