Ahh interesting, I assumed it included things like bonuses and equity, but am surprised to learn 401k contributions are not considered TC. Is this the case even for matched contributions made by the employer?

Meaning if I contribute x (money I was compensated already as a portion of salary), and employer contributes %/x (money the company effectively "gives" me), is that percentage not considered part of the "TC" terminology? OR am I exhibiting an unfortunate misunderstanding of 401k matches?

The rubric for all of these complicated and indirect forms of compensation is "benefits". These benefits are significantly limited in terms of practical cash value and rules around their use by regulation, whereas there is no bound on TC.

For example, an employer who does a 1:1 match up to the IRS limit would be contributing at most ~$20K to your total comp, but when you're dealing with the rest of the package being in the $500K-1M range it tends to get glossed over.