Well, we might as well cut the word 'almost' out of the dictionary then, as there is clearly no need for it.
I did not contradict myself, I just disagreed with you. You can only pass or fail your driving test, but you can make lots of errors and fail comprehensively or you can make one minor error more than the allowed number, which still means you failed, but only just. So you almost passed. Just google "almost unique" and you will find plenty of authorities that agree with me. Even one that appears to agree with you (English Grammar for Dummies) then gives an example that the writer considers to be correct - 'nearly perfect'. I can see no difference in principle between 'nearly perfect', 'almost perfect', and 'almost unique'.