Flying drones, for me, is a fun hobby and I like to share my joy of flying with anyone who wants to learn. Ive made many new friends and customers by being friendly to onlookers. Since drones are sort of new to people, most are amazed at them, especially something as big as a Phantom or Mavic. I have had dozens of people inquire about my drone when they see it, but nobody has ever been rude and interrupted a flight to ask a question. They always wait until I acknowledge their presence. If I see someone who looks like hes gonna ask a question, I usually ask them to wait until I land and then they can ask me anything.
If you or your friend dont want people to watch you fly, you might wear a hardhat and construction vest to make yourself look more official, and then maybe people wont watch as much, but people are people and are always curious.
I have also had numerous police officers watch me from their cars as I fly, but have never been hassled by them, they were just curious too.