If you consider how much smuggling goes on, while a hassle it's a necessity.  I have no idea how the border in the parks is monitored.  What's to stop you from paddling/walking across the border and back?  If you do a loop, how would they know you left the country?

A couple years back some asshats with guns behaved like asshats, threatening campers, cranking off rounds.  They crossed the border.  They were charged on both sides.  A good use of the border imo, take asshats like this out of the park on both sides.