My understanding is federated "payment" systems are difficult. I think there is active discussion on the topic, but I'm not sure where code/development is at, or if it's even started.

I think flohmarkt ("federated decentral classified ad software") is the closest we have right now. It has low (~10-30) Monthly Active Users (MAU), but is in active development.

You mean as in an auctioning platform? That's legally a bit harder to achieve, as auctions usually have the rule that if nobody outbids you, then your offer is binding. To enforce that, instances would need to verify your identity. That's easy for a larger company to do, but not that easy for hobbyists.

And then, to be federated, you would also need to make sure that other instances that you federate with uphold that standard.

Also, if you do auctions across international borders, how do you even prosecute somebody who does not obey the rules of an auction?

We could start a buy/sell/swap space using existing Lemmy technology, if we left the messy details for users to figure out for themselves.

Messy details add up quick, though. Payments, currencies, mailing addresses, reputation, conflict resultion, returns, scammers.

But "Craigs List" solved basically none of that on day one, and went on to be pretty successful.

So it's possible.

I mean theoretically, sure. Realistically, no. Because people would reneg on their offers, and you have no recourse as a seller.

That sounds interesting!
And even over 30 active instances are listed on codeberg: https://codeberg.org/flohmarkt/flohmarkt/wiki/flohmarkt-instances#a-list-of-server-known-to-run-flohmarkt.
I will check it out.

Biggest issue is probably that everything, including private messages, is public here. Not where you want to share your adress/phone number.

Yeah, it would be full of scammers on poorly moderated instances or their own private instances. The legit instances would have to work constantly to keep themselves defederated from all the scammers.

Also, if you do auctions across international borders, how do you even prosecute somebody who does not obey the rules of an auction?

On that topic of international law ... how do you prevent users from buying and selling things that are illegal to buy and sell, at least in some jurisdictions? What do you do when users across different federated instances with different rules are trying to buy/sell guns, drugs, and child porn?

Services like eBay are part platform, part people. eBay's people do a lot behind the scenes to ensure it runs smoothly and ethically... AND they take a significant chunk of the proceeds. You could put up some free software that does auctions but you wouldn't have all those high paid security and trust workers working for you.

A federated ebay is basically impossible. For that you would need real time communication between different instances. Otherwise people on the sellers instance would have an advantage in winning the auctions, defeating the purpose of making it federated in the first place.

I have seen the fhlomarkets in the past, I’d love for them to take off but uptake is slow and usually it’s odd items at ridiculous prices.

I know there was a post on lemmy/piefed from a Melbourne based guy who added a site he was working on a few months ago. Not sure how it went but he was open to talking about how he set up and what he was hoping from it.

It wouldn’t need to be that way — if everyone puts in their max bid at time of bidding, the seller’s instance keeps that secret until the auction clears, and then waits for all bids to clear at the end and picks the highest, you would get the correct outcome.

Meanwhile in the middle the current bid price might be out-of-date by some minutes.

Auction sniping would not work but idgaf about that for sure.

Trust in the seller’s instance seems like it would be the hard part.

There was also Free cycle kinda worked for a while and was pretty basic