This is something I notice when, for example, I read reviews on Trip Advisor or even some emails and notices from the management at work.
I admit, I am one of the lucky ones. I never had any significant trouble with English throughout my school days and I know that some folk struggled. But we've always had dictionaries for spelling queries, computers have spellcheckers and Word can't resist sticking its oar in if you're writing a letter.
What's gone wrong ? Bad teaching, general sloppiness or has our intelligence nosedived in recent years 
?
BTW, my favourite howler is 'your' when the writer means 'you're'. So often seen.