The Brexit project placed a huge bet on that, and it seems they are losing.
> this is news to me, and I can't find any evidence of it either
It was widely reported at the time. Here you go:
https://www.theguardian.com/politics/2018/dec/07/norwegian-p...
> the UK government has never had any interest in remaining in the EEA, which the EFTA requires
Perhaps, but nevertheless they were preemptively rejected, as you can read in the above article.
> when future treaty modifications occurred the UK did not veto the changes (its right), and permitted the changes, remaining under the rules the members had previously agreed
They did not only "permit the changes", they signed the treaties. Including the obligation to join the Euro, something that the UK never intended to do and everyone overlooked because they were the UK. That kind of special privilege is gone. By the way, the initial treaty that the UK signed already spelled out the goal of an "ever closer union", but then the UK politicians and media make Pikachu face when they rediscover this goal, and claim that they were deceived and that "it was just a trade agreement, never a political project".
And the rebates also existed, and had nothing to do with vetoes or treaties. It was outright special treatment. And still the UK kept complaining about its "contributions".