There is no rationale for this practice at all, zero. JB have different law? Screw that. I have also thought about complaining to somebody, but first one needs to find out who, and then even after that, one has no way of ensuring disciplinary action on offending agent, or in fact any kind of enforcement action by relevant agency. Even worse, agents become bolder when no action gets taken against them. Malaysia, like Singapore (Singapore less so now), many things are done for wayang only.
There is one way to screw these f*ckers over, but only assuming that like in Singapore, anybody can pay money to find out who the registered property owner is. Here we only need to pay URA a few dollars to find out who owns a property, so long as it has a caveat lodged against it, and most do.
If it can be done in Malaysia, simple. Talk to agent, see house you like. Say bye bye to agent, find seller details, contact seller and make offer. Bypass agent altogether. Since agents want to play dirty, play dirty with them. They want to unlawfully collect 1% from buyer (thereby representing no one's interest but their own), buyer and seller no longer have any financial obligation to said agent. Use that against them, see what they have to say.
In Singapore few people do this because the practice of collecting money from both parties has more or less stopped. And if a seller tries to bypass an agent (assuming the agent had a direct effect on introducing buyer to seller), the owner will get sued and still have to pay comm. Assuming the selling agent has not been guilty of any wrongful action.
But in the case of these JB agents, their attempts to collect 1% from buyer plus however many % from seller is wrong, legally and ethically. No need to play by their rules.
I paid 1% to agent when I bought my property because I was blur, and in the very first meeting with the agent, when discussing fees to pay, I already mentioned the 1% comm. Stupid me ha ha. But never again will I pay buyer's commission because such a thing should not exist at all.