5% is a lot if you spend (ten)thousands of RMB.

For the average tourist who might only spend a few hundred RMB at corner stores and markets (meals being included in their tour group arrangements), it's nothing compared to the convenience you get.

Spending 1000 RMB means 5% is 50 RMB, around 8$ or 6.50€. And that will buy you a lot, unless you decide to "splurge" (and then, most "splurge" places for tourists will happily take credit cards..)

So yeah, charging 5% but giving you the full convenience is a good deal. Obviously 0% (or something near it) is a better deal, but why spending much time if a quick and easy fix exists?