Upon some googling, the grammar seems to used for something akin to
Pattern 1) Noun[A] + ならまだしも + [B] [A] is the preferred option over [B].
However I'm struggling to see how it's being used in this sentence. The general meaning is that, going by top panel is that girl sneaked into the house where the criminals were, so they drugged her and dumped here somewhere else to settle the situation.
The dialog after says that it's lucky she didn't get killed.
My literal reading of the dialog would be something like:
"It would be better if it was America over not testing as missing girl for drugs"
...which I don't think makes much sense. From the previous page's context, I'm fairly sure they mentioned she got tested for alcohol. Going from context the only think that comes to mind is something akin to "It would be better if it was America. (here in japan) they don't test for drugs on missing people."
To sum it up, what is the exact structure of this sentence: