It's not a US-only phenomenon. I've got lots of similar incompetency stories from Poland.
My mom was a math teacher in primary school for 6 months after which she had to stop doing it because the kids drove her close to a mental breakdown.
Her friend from high school (which sucked at math) still teaches in her hometown and is seen by a lot of kids (and now adults) as completely incompetent (as reported by cousins growing up there).
I recall multiple instances of incompetency, abuse, blaming and general stupidity in my own education. Good teachers were the odd ones. Most were mediocre. The problematic ones had to really cross the line to get fired or warned.
My mom was a math teacher in primary school for 6 months after which she had to stop doing it because the kids drove her close to a mental breakdown.
Her friend from high school (which sucked at math) still teaches in her hometown and is seen by a lot of kids (and now adults) as completely incompetent (as reported by cousins growing up there).
I recall multiple instances of incompetency, abuse, blaming and general stupidity in my own education. Good teachers were the odd ones. Most were mediocre. The problematic ones had to really cross the line to get fired or warned.