> UPS and Fedex are in the top 100 most profitable companies in the United States, what exactly is your monopoly complaint?
UPS and FedEx legally cannot deliver letters, only packages.
> You really want to turn mail delivery into what the taxi system is today?
The taxi system today, like mail delivery, consists of a regulated monopoly that prevents competition and limits quantity (through the sale of taxi medallions); prospective competition has numerous restrictions placed on it (no spontaneous curbside pickup in the case of taxis, no letter delivery in the case of mail).
Yes, except the right to be a monopoly is not. I'm fine with the USPS existing, but you must let private couriers exist as well.