The hard part is getting enough trustworthy buyers and sellers online at the same time, in the same place, with payment methods that work. Escrow can reduce counterparty risk, but it doesn’t solve disputes, fiat reversals, or the cold-start problem—and every “trust” feature risks turning into a centralized authority.
Which has been the biggest bottleneck in practice: liquidity, reliable payment rails, or resolving disputes without a trusted operator?