We don't have to do anything, Craigslist already exists and works great. I've bought stuff from departmerting college students, the transaction is as simple as showing up and saying 'hi, are you X? Great, here's $50, thanks for The Thing'.
Some people just cannot be bothered, and if they're wealthy they simply may not care about concepts like wasting money - doubly so if they grew up with money and have never had to ration it for basic items. This isn't a market in search of a tech solution, any more than people who put out working items on the street with a sign saying 'free' because they don't want to go through the hassle of conducting a transaction for pocket money.
My experience trying to give stuff away online (or sell it for cheap) is similar to this Simpsons meme featuring vanishing Spock: https://i.ibb.co/0Vs9qHqm/116609166-3570105309667743-4078949... ... Although for the same reason, it's super easy to buy used stuff online just by offering the asking price and actually showing up.
Nowadays I leave unwanted but usable stuff by the trash room in my building, usually somebody will grab it, and if not it will get removed by the cleaning people eventually. I got a nice roller suitcase that way myself lol
My wife often sells things we are done with. If half the people who arrange a meeting to buy something show up she is doing well. Many times she has listed something for $10, has someone say "I really want this, will you take $20" - then not show up to meet. (we are always first come first serve, but if the first person offers $20...)
My wife doesn't have a regular job so she has some time to deal with this - but her time is still valuable (there are plenty of other things do to - I don't see how dual income families can raise kids!)
It's even worse if you post things for free. At least if there's a dollar figure attached to it, even $10, you won't get a dozen randos claiming they'll be right by, they can't live without it, don't give it to anyone else -- and then never show.
We have several times asked for a higher price just to weed out the non-serious people who will waste our time. We really just wanted to give it away to someone who would make good use of it, but charging too little lowers the odds of that happening.
Some people just cannot be bothered, and if they're wealthy they simply may not care about concepts like wasting money - doubly so if they grew up with money and have never had to ration it for basic items. This isn't a market in search of a tech solution, any more than people who put out working items on the street with a sign saying 'free' because they don't want to go through the hassle of conducting a transaction for pocket money.