Blockchain does not reduce the need for trust, in my opinion. If I order pizza from you and pay with Bitcoin, I still have to trust that you'll deliver the pizz

Blockchain does not reduce the need for trust, in my opinion. If I order pizza from you and pay with Bitcoin, I still have to trust that you'll deliver the pizza. There is no way around the need for trust (though of course there are mechanisms such as laws, police, and judges that help reinforce trust in our society). The only trust that blockchain provides is trust that a counterparty won't go back and change the ledger showing that a pizza was ordered. This solves the double spending problem, but it doesn't solve all the other kinds of fraud.