In America, most reputable companies follow a philosophy of "the customer is always right".   This may not always be particularly true in Europe.  For instance,I can remember dining in a restaurant in Paris a few years ago.  The waiter brought me the wrong dish.   When I pointed out the error, he insisted that I was the one who made the mistake and refused to take back my order without charging me for the original and the replacement dish.

On a recent tour to Paris, we had a problem with the hotel room in that hot water was not available until about 7 a.m. but we had some early risers who liked to shower earlier.   They notified the desk of the problem, they acknowledged the problem, the desk said it would be fixed as soon as they could get to it.  However, in typical fashion, they offered no compensation for the travelers' troubles.

I also find that discounts are different.   In America, it is common to give senior citizen discounts on things like admission to museums or travel tickets.  It is not so common in Italy for instance.  But in Paris, discounts are commonly given for those under 26 years of age.

On a trip to Italy, a traveler told me they purchased some time on a phone card.   When the card was not compatible with the traveler's phone, the merchant apologetically said he could not refund or change the card.

The examples above are just that, they are examples.  You may find the exceptions I listed above not to be true in all cases.

Another custom I find lacking in America is common courtesy.  It might be considered to be extremely rude in Europe if a merchant is not greeted with "bonjour", "ciao", or "hola".   Those magic words may go a long way to you and your foreign counterpart having a pleasant experience.