Well. In my opinion:
An eye test isn't really like a driving test or some other test you take to qualify you for some job or other. Though I suppose it could be - since it's something to do with driving. (But why would you want to be able to drive when you couldn't see properly?)
It's really about finding out how good or bad your vision is, so that they can fit you up with any necessary corrective equipment. So, my optician keeps on putting different lenses into this contratraption on my head and asking me whether things look more or less blurry with them in. There'd really be no point in me lying about it.
I suppose the chart on the wall is just a rough initial assessment guide - no more than that.
Oh, and it's always, as far as I know, the same chart. But I make no effort to memorize it. And I only have my eyes tested every 2 years - by which time I'd have forgotten anyway.