of sign inside or outside better

Got this photo from Laughing Cow

Recently these signs were pasted inside the lifts in my block. They used to have the sign outside the lifts.

I always thought that having the sign inside the lift is more appropriate. In case people are trapped in the lifts, they can call for help. OK it wasn't so appropriate in the past since handphones were not common in those days. But it's totally different generation now.