WTF Lawyers

..this is to enforce a uniformity of road signs and markings such that they can be interpreted by everyone everywhere to mean the same thing, and to allow the user to recognise an official marking or sign from an unofficial one... You might think this is a facetious argument, but this sort of situation was common before national type approval of road markings and signs.

Not facetious at all, standardisation is absolutely necessary. But I think there's a difference between specified design parameters to maximise functionality and what should be enforceable under law.

In the case of double yellow lines without T-bar terminations, anyone parking on them is not subject to a fine, because * they are not double yellow lines*
What are they then?

The T bar is required so that you know that the line terminates, and it hasn't just worn away.

If the entire line has worn away to the point of near or partial invisibility, fair enough, you cannot be expected to respond to something that you cannot see. But if the T end of the line has worn away (or not been painted) what difference would it make to how the rest of the line should be interpreted?

It's actually an example of a very well-drafted law.
"To impose a restriction on parking, this is exactly what you need to paint in the road" - no loopholes, no grey areas, just something that you'd think would be easy to implement.
Agreed, it should be implemented properly, but it should also be interpreted reasonably (again for a given value of "reasonably" etc etc)

I think road law is actually a situation where the loophole test would uniquely applicable because you are effectively told what you can and can't do in every specific situation. For example, there is no ambiguity over what 20mph means (as opposed to what something like "dangerous" or "threatening" means). The fact that the sign is bent (as long as it's still legible) does not suggest that it means anything other than "your speed must not exceed 20mph".