[tsimionescu]

> Physical cash or coin, exchanged between parties, is trusted by both parties yet leaves no transaction record.

The cash/coins are the record in this case: that was the point the GP was trying to make. But, they are not required for the transaction to take place: a trusted ledger also works.

> A finalized and appended bitcoin block needs no further trust. It is settled.

Of course it needs trust: you have to trust that Bitcoin is doing what it promises. Every time you sell something in exchange for bitcoin, you have to trust that:

- the network is working as advertised

- your client is working as advertised, it's not infected with some Malware to report the wrong info to you

- there is possibility of a 51% attack

Also, the latest finalized and appended block often changes. You actually have to wait until there are several other blocks appended after the one that contains your transaction until you can be sure the transaction won't be reverted.