why are sellers to be trusted, but buyers are not?

I guess at some level this is an "elasticity of supply/demand" thing. As a frequent buyer & seller, if I woke up tomorrow into a world that operated on "payment after receipt" - then looking around here, my answer for that is "I’m just not gonna sell anything online...EVER". That’s a low elasticity :) 

By the numbers, buyers have been more willing to put up the risk of "money up front", than sellers have been willing to eat "payment after receipt".

So, still a perfect rebuttal. I also bought a car that I only paid for 2 days after I drove it off the lot.

D-uh. You were present at the dealership and did the paperwork including your driver license, SSN and credit history. Please use common sense while responding.

I have had many buyers try to commit fraud on things I sold them. 3 times, I had people issue a complaint to PayPal that they never received the item, but they all forgot they had to sign for them which I gave the proof to PayPal. Plus I’ve had multiple people tell me the item didn’t work when I sent them a video of it working before I shipped it off. I told them that if they sent the original piece back to me with my documented proof of what I sold them (serial #, a certain piece of info on the unit itself that only I and PayPal would know, and after I told them this, they decided it was working fine.

it is well known that people buy working stuff and ship their old non working stuff back to the seller and PayPal gives them a refund, so the seller is screwed. Also, I found out years ago that selling overseas, signature doesn’t work past customs, so somebody can state they never received the piece and the seller can’t check if they signed for it or not. 
PayPal almost always sides with the buyer. PayPal F&F used to work but not anymore. So the latest stuff I’ve sold involved the buyer wiring money. I always request that the buyer comes to the house to listen to the equipment, check it out, then they can wire me the funds. I’ve had 4 people drive 400-1100 miles to pick up speakers, and turntables that I had all the boxes for but refused to ship them. 

The simple way to eliminate the perceived imbalance is to go to the seller to pick up your item.  If you don’t do that, the seller says “I’m willing to absorb the time and expense to ship (read: deliver) it to you - in exchange for you paying up front (with a third party escrow to cover your risk at a relatively small cost.”)

@ibmjunkman 

The CEO's of UPS and FEDEX state that it is network configurations and technological advancements that require the yearly 5%+ cost increases.

I was not arguing the merits or demerits of lost packages, but since you brought it up you need to take into account that each of the carriers have economy options that do not have guaranteed delivery and can- as you found on Reddit - have shipping movements that are perplexing.

If one were really to dig into that, you would find they are simply aggregating shipments and while it may seem ridiculous, one must understand shipping processes that are designed to save costs over direct routing. Think of it as, "well the truck goes there everyday and while in the wrong direction, we have a truck at its destination (a larger distribution center) that runs daily back to its final destination". Basically, its operations, and there is nothing odd about a package designed to be economically shipped going opposite of where it is meant to land.