"Private citizens" refers to individuals who are not acting in an official capacity or representing a government or organization. They are regular people who have no special authority or specific responsibilities. Full definition
There are some exceptions due to security concerns (i.e., they get security as private citizens who could be at risk). (politics.stackexchange.com)
Some bears were relocated; others were killed by private citizens as a nuisance or shot by hunters. (discovermagazine.com)
What is traditionally thought of as a military technology is about to change the lives of private citizens as well as big businesses. (newscientist.com)