I can whine about this topic all day long. Well, I am not a perfect speller or use correct grammar 100 percent of time(English is second language for me). However, my past job was a high school science / healther teacher(9th grader). If you have ever grade students' hand-written papers, you will be amazed how they write. In my opinion, there are two main reasons why so many mistakes occurs.
1. Most of my students write like the way they converse.
--> They write like how they type online. i.e. BTW for by the way.
2. They are lazy students.
I always have more than 5 English dictionaries in my classroom. However, my students always ask me how to spell words. I finally said this in front of class - "Think about this - You are asking a foreigner to spell an English word for you. What is wrong with that picture. You suppose know more English words than I do. Please look it up in a dictionary."
adreamer