(1) - The 2013 MBA does not run the same version of 10.8 as other MacBooks, as it's specifically coded for Haswell. It very well could be and most likely is a software issue.
(2) - That's a very generous number? Where are you coming up with that? 80% users sampled, perhaps - but I am quite sure it's not 80% of units produced.
(1) Really? Oh I didn't know that. Actually a little relief for me. It's nice to know that a software update will most likely fix this.
(2) While likely not most accurate based on circumstances, the poll at the top shows 80% of people who voted have this issue... well actually it's at around 75% now.
but to be fair, it is more likely for ppl with the issue to vote than people who aren't facing the problem.