Why does Safari stink?

I started my day with several calls from our Special Ed folks who suddenly couldn't access their student information portal (e-Sped). I could access it without problem, our Special Education administrators could access it, but several teachers and counselors were discovering (since this was the first student day back at school) that e-Sped simply didn't look right.

They reported intermittent login problems, data not appearing in forms, navigation troubles, etc. Feeling like an epidemiologist hunting down the source of salmonella outbreak, I started looking at what made these users different. It probably won't surprise anyone that they were using Safari.

Some of my Mac users were fine; these users were running Firefox since I'd had it installed on most of the new Macs we'd rolled out this summer. Anyone who had reverted back to Safari or who my techs hadn't gotten to yet was having problems.

Sometimes Safari works just fine; there are plenty of sites though for which things just aren't quite right. Since Apple tends to do a lot of things right (and their OS is a model of usability), what happened with Safari? I'd love to blame sites that cater to IE's lack of standards compliance, but Firefox handles these sites just fine.

So why did Apple drop the ball here? And if your users are moaning about e-Sped, check their browsers.