They don't own the entire network from your PC to the site you are speed testing. Also when others are speed testing, the speeds drop. How are you going to get everyone else off the internet so you can test the speed?
And then we talk about TORRENTS. Those speeds are iffy at best.
my provider is Comcast and I must admit that they irritate me with the lack of service. But, I've been tracking my internet upload and download speeds over of the last year using Speedtest.net and they're both consistently below 2000 kb/s. Seems to me that I'm paying for better than that but don't know for sure.