Bitcoin transfers are usually irreversible when there is at least one confirmation. This makes it hard for attackers to reverse without controlling significant percentage of the network or a long block reorganization... If transactions are reversible, the first option will never exist. Unless you are talking about a Paypal/bank approach which allows for chargeback. However, it is a must for a neutral party to meditate the transaction. With Bitcoin being trustless, the only way to do so is, as Amph mentioned, Multisig with escrow or a third party service.

Also, merchants can accept Bitcoin with little to no cost or loss. It wouldn't make sense if the merchant only wants to install a POS with Bitcoin integration when there is a large volume. Transactions are verified instantly by nodes when transactions are sent. If you're talking about confirmations, there isn't a need for confirmations with smaller valued transactions such as buying a coffee due to the difficulty of initiating a double spend as of now.