This is like claiming to be working as an electrician and not knowing how electricity works.
Someone who uses AI to code or make images isn’t doing machine learning anymore than a pilot is doing aerospace engineering. And someone claiming to be an aerospace engineer can’t say that they don’t understand fluid dynamics.
If someone is claiming to be in the machine learning field, not recognizing a fundamental technique of machine learning is a dead giveaway that they’re lying. This kind of diagram is used in introductory courses for machine learning, anyone with any competence in the field would know what it was.
Outside of low dimensional toy models, I don’t think we’re capable of understanding what’s happening. Even in academia, work on the ability to reliably understand trained networks is still in its infancy.