Card fees are often 3% and vendors have to increase prices to cover this. People paying cash are already paying these same inflated prices to cover credit card fees.
Luckily not everywhere. In Thailand cash (and bank transfers) are king. Most places do not accept credit, and the place that do usually require a $15 or $30 minimum and/or you're going to pay that extra overhead yourself. Alternatively, like when I bought my monitor recently, folks will just give you a discount for paying via cash/transfer (high value items like that often end up as credit charges or interest loans through the bankers).
