This is definitely illegal. Surely it is even illegal to track your employees by their phone even when they are on company time, right? If it is considered illegal for police to use tracking devices on vehicles without a warrant, surely employers are subject to the same laws, if not more strict rules.
I am not sure about this. App was installed on company provided phone.
there are certain rights that one cannot sign away.
On the other hand, she wouldn't have had to uninstall the app were she to have left her phone at work.