I'm glad you took my remark in the spirit it was meant.
It's such a good question that I'm surprised I've never thought about it before.
Well I sat for a while and was going to write some conjecture about Lion's vision possibly being slightly different - so thought I'd Google it and guess what? Lions are color blind. (Maybe I'm the only person who didn't know this).
So the wavy lines of a zebra blend in perfectly in the tall grass.
Also (from How stuff works and as per your initial comments) -
'When all the zebras keep together as a big group, the pattern of each zebra's stripes blends in with the stripes of the zebras around it. This is confusing to the lion, who sees a large, moving, striped mass instead of many individual zebras. The lion has trouble picking out any one zebra, and so it doesn't have a very good plan of attack. It's hard for the lion to even recognize which way each zebra is moving: Imagine the difference in pursuing one animal and charging into an amorphous blob of animals moving every which way. The lion's inability to distinguish zebras also makes it more difficult for it to target and track weaker zebras in the herd.'
Also zoologists believe that the stripes are like fingerprints and allow zebras to recognise one another.
My one issue is how does a series of genetic mutations create such unique, beautiful and delineated markings.
But I know that confuses a few concepts and I am willing to accept that as you have said elsewhere 'it's simple ignorance'.
There must be a mathematical view.