There's very few people for a reason

Who wants to learn German from a non German native speakers? 

If I see a Chinese person teaching German, my first impression would be this is not right.

Also it is true very few people want to learn German in the U.S. There's not much usage here for that for a few reasons:

1. German is not the target language for intelligence purposes so government agencies and miliary don't need it.

2. Ordinary people here don't like spending a lot time learning a foreign language, except for a few fanatics. 

3. German isn't something easy to learn either. 

4. It's not required for tourism. In Berlin and other hot spots most residents speak English very well. Unless you want to go the places not friendly to English speakers, like the Bavarians, you don't need to know any German. But most people wouldn't want to learn German for that purpose either. It's not helpful to learn German when the locals are hard to please with the language. If they don't want to speak English with you, then most likely they don't want to hear you speak basic Germans either.