Do you not understand how it works, or not understand what you're saying? Strava has nothing to do with the accuracy of speed reported, because it only displays data inputted. What you're really saying is that GPS isn't accurate, which is a misleading statement. GPS can be very accurate, and GPS can be very inaccurate. I don't know if that's a surprise to anyone other than you, so I won't go into why that is the case here, unless you did not understand my earlier explanation to you and would like for me to explain again?