See, I had one of my friends say thanks for the editing. Except that when I beta-read my brain is in a different gear from when I am editing and when I am reading submissions my brain is in a different space from either of those.
When I read submissions, I read them as a reader would. I don't see the typos, grammatical mistakes, etc. As long as the story holds my attention, I continue reading. If it doesn't hold my attention for any reason, then I pass on it. This leads me to a huge stack of stories that do hold my attention that I have to then go through again when considering submissions for Emerald Tales.
When I beta-read for a friend, I don't see the punctuation and grammar mistakes. If I notice one, then I mark it, otherwise, I am reading for flow, for plot holes, at characters and their reactions, looking for things that don't make sense.
When I am editing a story, my teacher's brain is fully engaged looking for the typos, punctuation, and grammar mistakes.
I don't know if agents and other editors are the same way. It would be interesting to find out.