I feel most mainland businesses and sellers don't want to get involved nitpicking the Hawaii law, and it's not worth it for them. Hawaii has a lot of firearms owned, but very few owners compared to mainland states, I think it was 7%? So on a national scale, Hawaii probably makes up well under 1% of sales, and AR magazines are probably a lot less in that 1%. So it's not worth their time or money to consult with lawyers, spend time debating if the law is valid or not, possibly get fined or lose their business, get bad publicity, etc just to make pennies.