Concerning money changers: They all claim no commission, but they have two exchange rates. Isn’t this a form of even g’dola and even ktana? let them take a commission for their service, but don’t violate Torah!
In a formal sense, money changers would not be transgressing the prohibition of even g’dola and even k’tana, because the two rates they use are publicized for all to see. The prohibition of the two stones refers specifically to deception, meaning the secret use of two sets of weights. However, it is true that the statement of “no commission,” is somewhat deceptive, and might be misleading, thereby ‘bordering’ on the prohibition.