In order for you to be convicted of Reckless Driving by Speed the Commonwealth has to prove beyond a reasonable doubt that you were in fact the driver.

In the vast majority of speeding cases, the officer simply observes the driver and clocks them with a radar or lidar device and then pulls them over. However, there are some limited instances where the officer may temporarily lose sight of the driver and then find them again later. In that scenario it might be hard for the officer to prove beyond a reasonable doubt that the person they pulled over later is in fact the same person they saw driving earlier. Perhaps it was the wrong car altogether? Or maybe one person was driving that car the first time whereas another person was driving that car the second time?  Moreover, there are limited times where an officer may get a call about someone speeding, but by the time the officer arrives on scene that suspected person is merely standing outside of a parked car that matches the description made by the caller. Once again, the officer would have a very hard time proving beyond a reasonable doubt that the person standing outside the car was in fact the driver that the caller observed.