Proofreading is a skill that is not taught anymore. It used to be that newspapers were impeccably proofed before they went to print. In the local newspaper, there will be spelling or grammatical errors that occur with enough frequency that it is no longer humorous.
I also read an article recently where businesses are having to train new hires to write letters and memos. The person quoted in the article said that schools are not teaching this skill with enough frequency that it is making a lasting impression. The person went on to say that one new hire, who was a college graduate, used "cuz" instead of "because" in an internal company memo. This was the company's "aha" moment that they had to start a training program to address this.
How this decline has happened in the span of only two generations is as breathtaking as it is sad.