JBL has since inception ( more-or-less ) partially followed the electrical convention where
the "Hot" wire is Black while the Neutral ( return wire ) is given some other color .
JBL ( on their drivers ) typically uses the black terminal as the terminal that will give forward cone motion ( with a positive pulse applied > say from a battery ).
Who-ever choose the color-coding of the network wires ( that you're looking at ) was most likely simply trying to remain true to JBL's historic color-coding convention ( even if it is seemingly backwards to the rest of the industry ).
FWIW, since audio is AC, the ( series ) passive components in a crossover can be on either network leg ( even both legs ).