Presumably you mean "second party", because the concept here is that there is no middleman. EDIT: to clarify, I'm sure there are cryptographic solutions which prevent an escrow agent from doing anything beyond releasing the funds. A system of escrow that involved total trust in the third party escrow service would be an extremely basic proposition. I'd have to research it but it seems like a protocol probably exists; maybe part of the techniques to which you referred. Still, both parties in the transaction count on the escrow service, which is the trust I am talking about.

The example system you mention, which involves having faith in (for example) a courier's delivery notification service, seems to me underline the ubiquitous implicit relationships of trust we implicitly rely on currently, generally being of the form "individual trusts institution/infrastructure".

It hardly needs saying that cypherpunks don't like that unreciprocated trust, or even deny its importance to their own security.