Why is my tracker inaccurate by a few metres?

GPS trackers are prone to a phenomenon that happens as a result of meteorological, atmospherical, and network disturbances.

But also this can be caused by bodies of water, buildings and irregular landscape.

This is known as "static drift" and causes variation in detected location. 

Rarely this can be larger than our rated accuracy of 10M. 

This is usually worse indoors, where GPS signal is weaker and less accurate, your mobile phone may be more accurate as it uses your WIFI to localise itself in poor signal conditions. 

Please place the tracker in your vehicle, you'll see that when the device is moving on a journey, that the accuracy is much better. This is because GPS signal is stronger when moving.