it's quite likely that the slaps on the wrist for correcting bad spelling/grammar were of a political nature. With universities (thanks to government initiatives) preferring overseas students to local talent. My father noticed a curiosity at my graduation: the vice chancellor did not shake the hand of any of the overseas students. I have seen several assignment papers written by overseas colleagues at uni., and the papers were hardly understandable, let alone of a university standard...
At work I've found Australians to be the worst spellers, even well read individuals.
My own spelling is not perfect, but i'm a compulsive (bracketeer) I guess an overflow of connected ideas makes for some atrocious grammar and lengthy sentences.
A number of unscrupulous individuals have cashed in on people's typing/spelling mistakes, by setting up XXX websites on domain names that are misspelt proper names, eg. dinsey instead of disney.