The king wants to be seen as a man of the people, so he lets commoners speak freely to him.
Vince is a peasant who leases from a royal estate. The King sees him enough times to be familiar with him.
Vince is the king's manservant.
The King is a Barbarian Hero who started as a clan chieftain. Maintaining informality is a necessary part of keeping his warrior's loyalty.
Vince is really the King's personal spy.
Access to royalty is so tightly controlled that Vince doesn't even know the king's real name or what he looks like.
The king randomly shows up at Vince's house.
Subverted: Vince goes up to the king as if it's seemingly normal, until the king orders his guards to drag him to the dungeons for insubordination.
Double Subverted:...where the king meets them again, revealing the entire thing to be a prank on his good buddy Vince.
Parodied: The commoner Vince has his own room and gang of servants at the palace for no reason at all.
Vince talks to the king as if it's normal in one episode, but in another episode he has to wait nearly 2 weeks before his request for an audience is granted.
The King is only willing to meet with some commoners; others have to go through various extra procedures, unless they have information that their ruler simply must hear immediately...
During Vince's first visit to the palace, he is stopped by palace guards and asked severely why the hell is he trying to waltz in. After hearing that Vince carries an important message, he's allowed in, only to give the letter to some royal servant. However, after reading the letter, the king is interested in Vince and invites him for a personal conversation; since that time, everyone in the palace knows Vince and he is allowed in with no questions asked.
Vince never goes to the palace or sees the king outside normal circumstances.
Vince has to wait for an audience as normal.
Vince doesn't even live in a monarchy at all.
Enforced: Vince is the protagonist of an RPG, and the programmers didn't want to force the player to jump through all sorts of hoops just to access the King and the quests he hands out.
Lampshaded: "Is he allowed to just waltz up to the king like that?"
Invoked: To show the idiot king just how bad of a job he's doing, The Good Chancellor convinces the king to relax his security for a short period of time to allow his subjects the time to express their dissatisfaction.
Exploited: Vince casually waltzes into the throne room, since he's allowed, and stabs the king.
Defied: "Talk to the king about it? Are you nuts? They'd never let some common schmuck like me into the palace!"
Discussed: "How did I just go up to the king like that? I paid off the guards, that's how."
Conversed: "So why did they let that guy just stroll on up to the king again?"
Deconstructed: Though warned against such lax policy, the King doesn't believe that any 'lowly commoners' could seriously threaten him. This attitude comes back to haunt him when an assassin disguised as a common farmer comes in to speak with him.