Interesting. A few people have told me that I enunciate more clearly than a native speaker, so if that's the case then my experience with speech-recognition systems will not be representative. With that said, older speech recognition systems did have trouble understanding me whereas newer ones don't so I think there really has been improvement.
I tried to find data about how students fluent in English do on this test but I wasn't able to. Comparing native English speakers to native Spanish speakers who have already learned English would be informative.