Is it rare for a mouse to come out of hiding when someone is in the room and with the light turned on?

Rodents have quite a small sphere of perception. Only a few feet really. They have an acute sense of smell but their vision is limited and hearing doesn't always provide information about the proximity or direction of the source of a sound. And if a sound can't be attributed to a particular source then they may not appreciate it's something they should avoid. 

So it may not be a question of feeling safe to come out but more that it was oblivious of your presence. 

I have mice that frequent my garden, when I go out I can hear them stop scurrying. After I've stood still for just a minute or so they carry on until I make a sound and they freeze again. Mice aren't the most astute creatures around, they're usually quite dopey. 

They may if they feel safe. A regular thing at my grandmothers house as she gives them treats, and sit in the middle of the floor nibbling away. No body chases or tries to grab them though and come right up to my grandmother.

Startle your little fur ball you may not see it for a while. Scavenging for food.

Not all animals fear humans. Even the ones that are said to, or normally do. Every living thing with a brain has it's own thoughts, opinion, and personality regardless of how large the brain they have is (not a pun or joke - mice have very small brains but are also very intelligent, most reptiles have very small brains too and some of them like alligators and crocodiles have survived for milliions of years so they're 'smart' enough to have the sense to adapt, learn, etc.).

Or perhaps it's not truly a wild mouse. Maybe it's a domestic mouse, it was someone's pet at some point and got loose and learned how to survive without it's owner feeding it. That would also make sense of why it doesn't behave like most mice do.

There are other variables and factors it could be too like the light in the room producing some heat so it's warmer in the room in the light than it is in the walls or wherever it normally hangs out and things like that.

I don't think it is necessarily rare. I was sitting in the garage and saw one do the same thing.