This was about one incident with the TSA, not with any airline.
You clearly didn't understand the difference in what you wrongly thought was an example.
It's a bit more complex than you might imagine. Yes, there are airline issues, TSA issues, and airport issues. Issues with an airline can become issues involving the TSA. Make no mistake about that. There are times when one might assume that an issue encountered is the responsibility of the airline when in fact it is an issue with the airport or even with a specific terminal! Yes, that happens. Resolution of issues, especially those involving the airport or terminal are in my experience almost never resolved.
The Air Carrier Accessibility Act of 1986, following several successful challenges by the airline industry, has been rendered largely ineffective. Anyone not surprised? What recourse do citizens now have? They may file an administrative complaint with the DOT. Good luck with that.
Attempts to bring acts of discrimination, as they occur, to the attention of the airline or the airport may then involve the TSA (if the airline notifies them) where upon you may miss your flight, encounter a bit of rough justice and/or even end up on the no fly list.
Personally I have had nothing but good experiences with the TSA. I don't fly as much as I used to, now maybe only 6 to 8 times a years. I fly out of Phoenix where the TSA is generally professional and courteous. For what it is worth I have noticed that back east, and down South, the TSA is less courteous and more militaristic. And they scream more.
In closing I would say that flying ain't what it once was. Now flying is pretty much the same as taking a Greyhound Bus from Buttwaddle, Kansas to Dirt Squat, Georgia. It is stressful and frequently unpleasant. There are more and more first time or infrequent fliers these days who are not at all familiar with the system. As a result more stress is added to a stressed system. Everyone working in the commercial airline system is fairly stressed as the paying customers are close to miserable throughout their travel day/night.
The airline industry pays members of Congress big money to be able to legally abuse paying customers with little fear of any real retribution. The American flying public is fairly ****ed and has little recourse. It isn't a happy system.
I've never seen a TSA beat down but of course, as with the OP, it happens. The lady in the OP could not have been considered a threat of such magnitude that she deserved being beaten and bloodied by agents of her own government.