Private transactions are not subject to statutory consumer guarantees. Still, trading platforms where private buyers and sellers meet (e.g. eBay, or TradeMe in New Zealand) do provide some level of protection for both of them and dispute resolution process.
Are they legally obliged to do that in any English-centric jurisdiction? Or do they do that merely because it repels crooks and makes their service more attractive to honest traders?
In other words, would it be a legal business to run a trading platform that only matches buyers and sellers but does not give them any guarantees beyond that?