They do know that if the people have the bottles inside there is a good chance they won’t be tracked. GPS won’t pick them up.
The tracking chips would not be inconspicuous either. You can get a small GPS tracker that simply stores the location data for later retrieval. However, if you want one that can transmit its location, it is going to be at least the size of a pager/garage door opener. So, I’m sure any bottles equipped with this technology would be significantly larger and easy to spot.