You can do some jobs at a distance, without much interaction with other people. For instance, Upwork is a company that connects people who need work done, with people who want to do the work.
Be a Ninja
Consider the origin of the word "eavesdrop" - it relates to the "eaves" of a house. A person wanting to overhear what was being said in a house (a spy) would conceal themselves in the "eaves" to listen.
only if no ones there to see it (a doppleganger is not a ghost its just someone who looks excactly like another person, but not related)
In the Aeneid: Book I, Venus conjures a cloud to shroud Aeneas and his friend, Achates, so that they can enter the city of Carthage without being seen.
Blend in with your enviorment and act normally
No, but they certinly help your image. Ever seen Steve Jobs without his glasses? Not very insightful looking.
Be quiet. Moose get disturbed easily.
Probably.
so that it can hunt its prey without being seen
A person who cannot be seen is typically referred to as invisible. This may be due to being camouflaged, hidden, or possessing the ability to make oneself transparent.
A recessive trait is one that is not always seen. Recessive traits can be carried in a person's genes without appearing in that person.
ANSWER:Because he can and he knows he can get away with it without being seen.