Maybe they can be talked around but I've never seen it. And I'm bloody CHARMING. I've worked in prisons, with gang-involved youth, I've talked riot police around. Manipulating people is what I do for a living!
And I've met a couple of OK Immigration Officers, even in the US. But the TSA? I have no idea where they find them but they are properly awful. Maybe they go home to their families and kiss their children and are kind to dogs and old people but not at the airport. One of them the most recent time really rudely said, "I suppose you need a tutorial" to the nice man next to me as she rattled off (really quickly) "everything stays in the bag, shoes off". Well yes, he does need a tutorial because English isn't his first language and you are standing next to a poster with liquids and laptops out and shoes on. Literally right next to it. With pictures.
It's like they work in an airport and don't understand people speak different languages and are used to different things. And are tired, jet lagged, may have additional needs. They expect the travellers to be perfect at doing what they need to do, politely. While the TSA are shit at what they do, and aren't polite. They seem weirdly drunk with power.
In countries with far worse safety issues, the security checks can be much more detailed but they still manage to be polite. China, Israel, Nicaragua, Egypt, the UK, all have serious security issues and all have nice staff. And nice isn't even the standard. Capable of explaining, politely, and keeping the queue moving.
This thread has been very cathartic, thanks!