I would start with high paying jobs like developers. Curate the community (companies and applicants) strongly, get the questions right, and then branch out into many other jobs, roles, and industries from there.
Also targeting freelancers from Upwork, Fiverr, and TopTal would be a great launching point to find hungry motivated applicants.
I think the solution would have to include some sort of logistics where a last mile delivery driver can pick up a return when in the area dropping off a package, meal, or whatever.
Think like how the mailman delivers mail to our homes but at the same time if you put your red flag on your mailbox up, they will grab whatever mail is inside and deliver it to the post office for you.
So that but for packages.
A few things to consider would also be, how often are frequent are these returns needed, and what is the value of these returned packages on average, and if there is a way to generally know the value of the package or what is being returned exactly.
I guess it will depend on the level of precision needed. Why have a money counter that "almost" counts exactly how much money you have. Because you'll then need to go back and more precisely count anyway.
There are some software/hardware cheat devices used in poker gambling that can accurately count a deck of cards and the order just from scanning the side. But I'm sure the way it works wouldn't apply to regular un-altered cash bills. Here's a link to the A7 poker analyzer device I'm talking about: https://markedcardsusa.com/products/a7-poker-analyzer
Maybe there's some overlap in creating a software and minimal hardware product to count cash from this product.