to compete with Private for Profit Insurance, because even though there will be other cost efficiencies in a Public Option (and it WILL, btw, be a VERY important question HOW those other cost efficiencies will be obtained!!!), providers will still have to maintain the costs of administering claims and payments.

Single Payer ALSO could provide enough cost efficiencies so as to allow expansion in the types of services provided, including PREVENTITIVE services, and a Public Option without Single Payer, having STILL to compete with Private for Profit on the SAME playing field will NOT be able to consider exapnsion of services UNLESS Private Insurance does and IF/when Private Insurance does do that, there is ALWAYS the question of HOW(!!!) they are obtaining the cost efficiences in order to expand services covered as long as they are ALSO carrying the extreme burden of the claims and payments processing mechanisms.

In short:

A Public Option without Single Payer is NO OPTION AT ALL.