Yes, some do add a credit card surcharge.
One that comes to mind is
Hotel Castillo. They add 15% to credit card transaction.
From their
website:
"Add 15% to above rates if you choose to pay by credit card"
I think the reason is very high CC processing costs. The banks in CR rape merchants on fees, and customers as well (as high as 70% credit card interest rates). That's why many places give cash discounts or at least are willing to haggle if paying in cash.
Last trip, my wife and I had an appt at the US embassy and had time to kill so we went across the street to the little strip mall. There's an electronics chain store ("Gallo" I think). I was looking at smart phones. They had a Galaxy, the price was something like ¢250,000 ($470) to buy it. They also had a financing option. I think it was 15,000/mo for 48 months, if I remember correctly. In the end, the customer ends up paying ¢720,000 ($1350). They even list the APR (66.67%)
