"If you can read this thank a teacher"

Meh. That was the phrase I saw on a t-shirt today. My thoughts were:
Define 'teacher'. No, really. I knew how to read before I set foot in any school. My mom taught me my letters and how to spell my name and she played lots of learning games with me. I watched shows like Sesame Street and I always had books. The first thing I ever read was written in cursive and it was in a Little Golden Book- 'this book belongs to _______' and my mom had written my name there in cursive. Everything just 'clicked' at that moment, and then I was able to read the whole book to my parents. No professional 'teacher' taught me to read or write.
I mean no disrespect to teachers. I just find the idea that 'if you have a skill then you should go thank a teacher' to be preposterous.