That is exactly the case. The problem begins with the catchers at the locations already. If they catch too little amounts of fish at a special place they will add others from a second location in the same bag if they look similar to the first ones. They have not the special perspective of the trained specialized aquarist and they are not used to the fact, that Parosphromenus fish are still differentiating by lively evolution even in near but distinct locations (as do Cryptocoryne forms in a similar way). Their employers, the exporters, either are equally well-informed or – more often, generally – are not interested in disclosing their productive locations. Their clients in Europe are unable to change this mentality and mostly factually unable to tell an exact location; so ist the shop-owner as last link in that chain.
We must try to inform the Asian partners that this would be necessary in order to pay attention to ongoing evolutionary processes, keep fish from different locations separate and not to mix them. From a biological point of view the clear naming of locations would be the best strategy, but the economic fears will prevent this. The best we can do is to name those fish with the safe names we have: their sellers and the year of import of that stock.