My french teacher couldn't speak french properly - she used to look stuff up in study guides and read it, pretty badly, to us. Much of the focus was on memorising lists of words rather than learning to build sentences etc. I don't think my experience was that unusual.
The argument that native english speakers shouldn't bother learning other languages because everyone else is learning english is common, but ridiculous. We all travel and migrate more than we used to and this trend will presumably increase over time.
Being the odd one out in a group because you only speak english feels like a disability in many places. It's especially embarrassing when the group speaks english to include you thus highlighting the difference even more.
I didn't know languages education was voluntary in the US. I would have assumed that most children, especially those in California, would be required to learn spanish. Maybe some french for those living near the border with french speaking parts of Canada. Correct me if I'm wrong.
It's well established that learning a foreign language is easiest as a child. Perhaps the best way to make a monolingual nation multilingual is to adopt a policy of favouritism in hiring teachers for young children who are bi-lingual.