The U.S. created the Internet, but its speeds rank 15th out of 16 major countries, ahead of only the Philippines. Mexico is No. 17, by the way.
It turns out that Son couldn't have been referring to the broadband service he receives from Comcast, since the survey data he was citing--as he has in the past--appears to be from OpenSignal and was gleaned from a subset of the six million users of the OpenSignal app who had 4G LTE wireless access in the second half of 2013.
Oh, and Son neglected to mention that immediately ahead of the U.S. in the OpenSignal survey is Japan.