WTF Lawyers

Sorry, but you are wrong.
The law specifically defines the form that a yellow line must take, and specifically says that no variation is permissable. The fact that it does 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. If they were not, a council in Leeds, for example, might decide to paint a completely different marking to denote a parking restriction and start fining people from Manchester who had no idea what that marking determined. You might think this is a facetious argument, but this sort of situation was common before national type approval of road markings and signs.

Yes, it needs to be consistent to be enforceable.

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*

Well, of course they're double yellow lines, they're just not double yellow lines with T-bar terminations. :)

and as such no offence has occurred and the attempt to impose a fine rightly has no weight in law. In these cases the council was perfectly well informed of the design they must paint, but they neglected to do so. It is incumbent upon them to paint the lines properly.

Yes, although I'm pretty sure that I've also read about cases in which people have vandalised such lines to render them unenforceable.