1) Outliers always have a particular reason
2) To find that reason without detailed analysis is pure speculation (some people might try to tell you "reasons")
3) ...actually, there can be MANY of them and I give you a list
c) undetected construction flaws
d) exceptional user behavior
e) .....
most of these can/will be fixed.
And again: We just could decide to not care at all, because these still consume much less than average "standard" new construction.