Tracking USPS Signature Delivery mail- WTF???

My son heard thru the grapevine thru his employer that the USPS has an agreement with Amazon, giving them preference in shipping over the general public.. and if any employee speaks out, their job could come into question.
When I asked the lady at the counter that, I got a very nervous denial.
Because it's true, the post office even delivers for Amazon on Sundays. Amazon also does a ton of government contract work with web servers. So of course a government agency is gonna help a government contractor before helping a citizen