There has recently been a controversy with Telepizza workers that has ended up in the Supreme Court, and in this case the company forced workers to use their own mobile phones to be able to record their geolocation at all times.
In the ruling issued by the Supreme Court on this case, it is clear that the problem today is not in geolocation, and it argues as follows: "It is not denying that it is a legitimate measure for certain purposes or that it does not avoid a competitive trade deficit, at a time when, certainly, this system of providing service to the customer extends to this and other sectors, but simply that what it has implemented does not exceed constitutional or legal criteria, when there are other ways of implementing this system other than this".
The main problem lies in the use of personal mobile phones to geolocate the place where one is working at any given time, and in fact this approach is completely aligned with the recent Law on Teleworking, which makes it clear that the employer must make available to the worker all the tools they need to carry out their work, including a smartphone if necessary.