A lot of employees are intimidated by their managers, or students by their professors.
Someone may also be nervous around police officers, high-status professionals like doctors and lawyers, religious authorities, or employees who have power in a particular establishment, like bouncers or bartenders.
Like they may start getting weak in the knees when they have to talk to someone at their school who drinks under age, occasionally skips classes, and who once tagged a mailbox with a marker.
In this case someone may need to just get more experience with the world and see that tons of otherwise good, nice people often skirt the rules in one way or another.
They can be scary in their own right because you worry you'll do or say something stupid around them and they'll call you out on it.