Because we can either do this inexpensively and inefficiently by having governments (regardless of politics) in charge of distribution or we can do it expensively and efficiently by having companies experienced in logistics handle it. We're running out of money, so inexpensive it is.
Can you imagine Amazon screwing this up? Neither can I. But Amazon isn't going to do it for free, and its workers probably wouldn't be properly protected or fairly paid, either.
Maybe putting the Army in charge is the right move.