<font face="Verdana, Arial, Helvetica, sans-serif" size="2">That said, I have no dealings with the TSA and am submitting my luggage to the handling and care of the airline. There have been instances (at LHR, specifically) that I have been summoned for a luggage inspection at the gate and in my presence. That would be different. As long as the luggage is in the care of the airline, though, I will hold them responsible for the condition and the completeness of the contents of the baggage. If they want to give it to the TSA or send my shirts out for cleaning, that is their call. I do not see why I should do it any way differently.</font>
Many airports have the baggage handled by carrier acceptance straight downstairs to the CTX machines (TSA) and then onto the carts and loaded onto the aircraft.
No airline chose to give any bag into the control of the TSA. Federal law says we HAVE to do so, unfortunately.
However, nobody should ever pack anything they can't afford to lose in checked baggage. Accidents and mistakes happen and nobody is liable for your lost "anything" unless it is clothing or shoes or toiletries- or the bag itself.
You're correct and I'm mistaken to say that the TSA is solely responsible for lost articles. However, if your bag triggers an alarm while being handled by the TSA and they inspect your bag- outside of the specific airline's control- it's your bag, your trigger and your responsibility to follow up for any loss or damages to the TSA- filed through the carrier you arrived on.
I don't understand your statement that you "have no dealings with the TSA". Yes. You do. The moment your ticket was purchased, you entered into an agreement with the airline. The moment you check-in yourself and your baggage- you enter into an agreement with the TSA. None of us are able to travel without the TSA's involvement.