I've contact with 2 different US accountants that will manage the banking for a company from really nearly anywhere. It costs around $3,000 per month, but they will recieve payments on your behalf to a US based bank account, make any payments you need, and at the end of the month move your profit to anywhere you want or hold the funds without any need risk of IRS implications.
I believe there are cheaper options out there, and those i'm still looking for; but certainly for my business, i need US banking, but with these options I dont need a US corporation.
Maybe the expense︀ doesn't make sense for selling on amazon, maybe it does.