I live in the US. Some cities have banned credit card surcharges. The bans have been wholly ineffective and achieving the desired result. I'll illustrate what happened at my local ice cream shop. This is a real example and not made-up for this comment.
An ice cream sundae costs $4.64. There is a 3% cash discount. So it's $4.50 when paid in cash and $4.64 when paid by card.
This is a credit card surcharge but by another name. And legal according to the rules of Australia's scheme as well. The only real thing that can be done here is to not patronise businesses who impose a surcharge that you think is unfair.