What's with the spelling errors?

Why everytime I read an answer or a question, there is nothing but run on sentances, mis-spellings, and other grammatical errors? Am I the only one that writes in complete sentances, and capitolizes the letters that need capitolization. I'm a writer, so I guess I just might be over reacting. But have people really become that lazy? Sometimes I can barely understand what people are saying. There was one answer I got that was written fully in abreiviations. Like 'da' for that, and 'r' for her. Come on!