Lots of difficulty getting a US credit card, even though I have US SSN, real business and banking relationships -- but I do not have any credit history or direct US income or salary on a personal basis.
Eventually we solved our problem with a Visa debit card. It works (and is accepted) as a regular visa, but the money comes right out of the account. No points, but I don't care. It was getting nuts exchanging US business income to Canadian funds, to pay off my Canadian CC for US$ expenses. The benefits of the points earned for Aeroplan were far outweighed by the costs on exchanging the money back and forth and back.