That is true as a general rule, but there are exceptions -- taxis in some countries, for example, where merchants are quite specifically allowed by the credit or charge card organisation to add a surcharge.
Don't know how they got it approved, but all Sydney cabs that take credit cards have a big sign saying card use will be surcharged 10% and you agree to that by using card.
There is a sign next to it, just as large, saying "VISA cards are not accepted by this cab", as I understand VISA refused them OK for the 10% surcharge. Went on right thru Olympics, and as the sponsonship thing is a big deal that would have p!ssed off VISA methinks - who were an anchor sponsor.
In fact rhe ONLY card you could place Olympic ticket purchases on (some were $1000s) was VISA.
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