yes, but there are some companies which would pick up the old stuff and sell it for you, taking a part of money received from sale. Maybe something like this will become even more popular. They can also employ handicaped ppl.
Yep, those are called consignment shops. I've never tried one, but it's not a bad idea in theory. But considering how little you might make from an Ebay sale for many things after Ebay and PayPal take their fees and then you pay for the usually-"free" shipping (with USPS rates already high and constantly rising, and UPS/Fedex rates even worse unless you're a big business), I do really wonder how profitable such a business would be.
I do list stuff on Facebook Marketplace. You still have to create a "proper listing": you have to take photos, and you have to do some kind of write-up if you want to actually succeed in selling it and getting a decent price. Listings don't post themselves.
For a phone, yes, $7 or so will ship it anywhere in the US with a USPS Priority Mail small flat-rate box. But for anything larger, the costs go up; I was kinda talking about the general case of selling any of your stuff on Ebay.
I do agree you'll make out better than some trade-in program if your item is small and high-value and you're willing to put in a little bit of work to list it, take some photos, etc. But my point was that many people are too lazy to do this work, especially people who value convenience over saving money (which describes Apple users to a tee).