Some don't care anymore
And some never did.
A few of my colleagues are shockingly slapdash and cack-handed. Some can't even be bothered to keep their tools or OS up to date.
They'd probably run Windows XP RTM if the IT dept would let them.
Perhaps they never cared, maybe they have been broken by past events or are just plain incompetent, but they exist and as acceptance and regression testing can never be perfect...