(I’m focusing this response on Game Industry Technical Art)
I personally think that your programmer example is an interesting one. On one hand it fits perfectly, because both a front end and back end engineer write code for a living, and are required to in the very least have a familiarity with each other’s domains. I will come back to this.
However I think your question is the crux of any sort of establishment of a career ladder. What IS tech art? In my experience different places define the role in a lot of similar ways while at the same time adding their own, non standard requirements.
For example, they may require someone who knows Maya, Photoshop and Unity, understands best practices and can code (to some degree). Then are are some places where they also require the tech artists to rig and animate, or be an expert in lighting and or also write tools from scratch. Sure sometimes these job descriptions have titles like Rigger/Animator, Lighting TA, etc. But often they don’t.
The other thing to consider, and now I am coming back to engineers, is that the one singular skill that all software engineers posses is coding.
When it comes to tech art, the core skills that we are often required to possess are no different than Non-Technical artists. 3D modeling app, image editing app and asset creation. I left the game engine part out of it because we are often required to possess a mastery of a particular game engine, whereas most artists and animators are only required to have, at most, a passing familiarity. Riggers for example can work their entire careers never having launched a game engine.
Where I work we have a good number of tech artists. And though we are mostly interchangeable, there are a few subtle differences. We have a few incredible riggers, though the rest of us could create and wire up a rig if we had to. Some of us are stronger at coding, and actually completely implement our features, and in some cases add features from scratch, into the client. Also some of us are really good at shader writing while others are comfortable lightly editing shaders. All of us are required to be really good with the software we use, so we can unblock and mentor artists and in some cases engineers, and we are even required to have the artistic chops to create assets if need be.
So though I concede that career ladders and specialization have helped better organize most developer disciplines, I also have a keen fear of pigeon-holing. For example animators are rarely asked to help with modeling and texture work, or even lighting.
I personally love the versatility and the diversity of our expertises and also believe that our strength comes from learning/trying new things. Though I do agree that an established, common guideline should exist for what is junior vs senior, being given a “category” of specialization can also serve to limit our opportunities to grow and do new things.
That is simply my opinion, and I could be entirely wrong, I also tend to ramble on.