Particularly on a very rounded base, the actual part of the glass which is in true contact with any surface can be absolutely miniscule and so invisible to the eye.
The only way to find it, is to run your fingernail around the area where contact would be and see if you can feel any wear.
Also, things that didn't get moved a lot don't end up with base wear.
But I can see plenty of base wear on that enlarged base pic!
Ben's vase is purple, there is no brown in it, the one you show, Paul, is more aubergine - even without something to compare it to, there is still a good hint of brown to it.