Unfortunately there is no easy answer to this question, as it depends on where you are and the laws of that particular country and region.
It is MindMyHouse policy however that if home owners have cameras or recording devices on their property, they must declare this to the house sitter before the assignment starts, so that this can be discussed and that there are no surprises.
We have tried to help by including a special declaration regarding this in our "House sitter agreement" document (in section five) which you can download before the assignment starts. In this section, home owners can declare the locations of these devices as well as the times of operation. Also, house sitters can declare whether they consent to the home owner operating the devices or not.