Counter question: where does it say on there that it's PD3.0?
From the power source it looks like PD2.
Perhaps it follows since stuff from the PD3 specs and that's why that tester said it, but this is guesswork.
Perhaps I'm misunderstanding you but the gist of your text is "why is this item not saying what a random guy said it should say??"
I've checked another Dell power plug, they don't claim anything on the box concerning standards they follow from what I can tell. Third party ones often do though.
My Lenovo doesn't say anything about that either interestingly, thanks for the rabbit hole! :D
Edit: remember that companies need to pay fees when they advertise with the standard - they can just follow its spec without advertising it at all, I can see that happening for laptop producers specially as they don't sell their power units as generic products (i.e. with a focus to market them).
