I personally agree that copying answers where the copier knows how to do it is a victimless act. But to take the position of devil's advocate here, one could say that there are actually potential victims.

One potential victim is an employer who believes they are hiring someone with objectively-evaluated qualifications. I think this argument is easily shot down; institutional evaluations are not actually objective, and in fact the person doing the copying is actually in a better position to evaluate their abilities than the institution. But, someone else may believe differently on these points than me.

Another potential victim is the person being copied from. They may feel socially pressured to allow someone to copy from them whether they actually want to allow it or not, and they may submit to that social pressure (and this isn't made up -- in certain circles it would be considered a little rude to not allow your friends to copy your answers). But if the institution finds out about it, both parties (copier and copiee) may get in trouble. While this is probably a rare case, it's still true that a person knowingly using that social pressure to their advantage is doing something unethical.

Anyway, I basically agree with you on this point, but it's fair to say that this issue is not as definitively clear-cut as you make it out to be.