They don't need any. The old paradigm was that the regional bought/leased the planes (saving the major the expense) but would thus require a longer-term contract (ten+ years) to minimize the tail risk on the backside of the contract. Several problems with this, on of which is the major can't unload the planes if needed, and if the regional sucks, they may not be able to replace the planes (this is why AW and then US never fired mesa...too inconvenient to lose the 40 900's owned by mag).

The new paradigm is for the major to buy the planes, and then Ho them out to the lowest bidder on a short-term basis. If things don't work out it's easy to swap operators, and they have flexibility every few years when the contract expires to rebid the flying or just eliminate it altogether. This essentially eliminates SKWs big financial advantage.