Olive racing, 10-15 miles is a huge range for a tiny battery powered radio with no significant antenna, and of course assumes that the owner doesn’t get the train 30 miles and ride the last five!
I’ve never seen any gps tracker smaller than a box of matches, there are some smaller radio transmitters that then rely on a network of receivers to pinpoint or triangulate the signal – probably the most well known being things like tile, which is still quite big – roughly the size of a two pound coin – to hide on a bike, in a position it can still transmit; and unlikely to be easy to track once away from the most densely populated areas (it relies on there being random members of the public, who also have the tile app running, within Bluetooth range of your Transmitter).
Once in your garage or house it’s very unlikely any miniature transmitter would both receive good enough gps signal and have sufficient transmission strength to share it’s location, so it probably only locates your bike to a small cluster of houses as the nearest last position unless you happen to live 50+m from your neighbours.
Tracking a car would be much easier as you can hide a much bigger transmitter quite easily.
