VANCOUVER — Chris Sweeney and his husband were driving home to Seattle after a recent trip to Vancouver when they were stopped at the border for more than two hours and threatened with thousands of dollars in fines for dangerous contraband in the trunk of their car. Their suspicious cargo? Half a dozen Kinder Surprise chocolate eggs, each filled with a tiny plastic toy — a childhood favourite in Canada but an illegal choking hazard in the United States. “I thought (the American border guard) had done his search and hadn’t found anything, and he was joking with us,” Sweeney,...