Why USians think we know languages when we don't

Earlier this year I posted about an unpleasant interaction I had with a Frenchman who lives in California. He scoffed at me for posting on my facebook page that I "know" French. I explained that the template for listing languages in your profile says "knows".  So don't blame me, blame Mark Zuckerburg.  It is probably more on target to say I study French.  What followed was his stubborn insistence that I was somehow being dishonest and a poseur of sorts -- pardon, poseuse. I was really exasperated by this.