Traditional Publishing versus Indie Publishing

I've just seen a blog post about errors in books that have been published by traditional publishers. It inspired me to post a comment. 

I'm reading a novel where there was NO full stop at the end of a sentence. A few years ago I read a novel set in 1983 which referred to the British Prime Minister as HE. Leaving out a full stop is forgivable. Editors are not perfect. But failing to know that a woman was the British PM is an unforgivable mistake. It wasn't simply that the s had dropped off or been accidentally deleted - it was a repeated mistake.