Will amazon ever require marketplace sellers to use UPS or Fedex? Its the only reason I dont use Marketplace.

Because the USPS is terrible. Never get things when expected, poor service, etc. I do not accept USPS mail because I had so many problems. Amazon puts their name on the marketplace and should want there to be as few problems as possible.

That's strictly your problem. I've been a marketplace seller and an ebay seller for over a decade, and the worst problems I've had have been with Fedex and UPS. I've sold thousands of books and cds, and collectibles all over the world and the USPS has handled 99.999% of them with no problems at all. I've had Fedex and UPS destroy items, send them to wrong addresses, and make me jump through all sorts of hoops to get satisfaction. Anyone has the option to ship however they want. The USPS is fast, dependable and cost effective for the majority of sellers.

I am sorry to say this, but if Amazon can sell billions of dollars worth of stuff and send everything via fedex and ups, they have proven themselves. Further, I do not know if you know this, but Fedex is the official post for international post that the USPS uses. Out of the 30K I have spent with amazon, I have never received a damaged package with UPS and Fedex. I also receive all my medical supplies through UPS and Fedex and have not had any problems (these are sterile and MUST be received on the day agreed for surgeries, post office cant make that guarantee). Also, the usps is losing money, just laid off 1/4 million jobs, etc. It is a known fact that USPS has not lived up to standards. I have found that amazon marketplace sellers will over charge for ups and fedex shipping options. Where I live, in New Mexico, to send letters locally takes a minimum of 7 days to deliver through the post office. While it is "strictly my problem", I would likely spend more money on the marketplace if they made it easier with a more reputable delivery options. Oh wait, that makes it the sellers problem too. They arent getting a customer.

Well then, we'll have to agree to disagree.

probably not.