Do you understand why your competitors work? They've spent decades building up brands like "When you abso-fricking-lutely have to have it there by the day after tomorrow, or it's your job." There are movies about their core value proposition and brand messaging.

Now after you understand how they work, do you understand which of their customers don't need to pay for that? Can you identify a group of folks currently shipping through FedEx who can switch to "eventual, best effort, may not actually arrive" delivery? An addressable group? A big addressable group?

If not, scrap the idea and do something else.

P.S. I think you are missing the "last quarter mile" problem, too, although it won't be a quarter mile for your implementation. I assume that in any given day there are a lot of packages going from somewhere in LA to somewhere in New York, but not one single package going from "somewhere in LA" to "somewhere in New York". They all have to go to a specific address in New York -- which means you need to find someone going to that exact address.