Your examples are not jargon, they're metaphors.

Some government websites are intended for a specialist audience. I think it's great that the site for paying my car tax is very simple but I would not expect the instructions for using a government data API to be written in the same way.

I don't think anyone is saying otherwise. It's clear that the discussion is about general public-facing government websites. Something for which the intended audience is a large portion of the population.

Your not recognising jargon from other fields. All of those phrases have precise technical definitions.

For example "360 degree feedback" is when a manager's direct report is asked to give feedback about their manager. In other words you give feedback about your boss, often to your boss.

It doesn't really make sense as a phrase or metaphor. It should really be 180 degree feedback because if you turn 360 degrees you're facing the same way that you started.... But that makes it even better jargon. It signals that you've been on some management training courses.

360 usually involves feedback from peers as well, hence 360.

Makes sense, also I'm now sure that you'd be a good manager because you've demonstrated a deep understanding of the jargon.