That was my observation.
Every bedroom needs two means of egress in order to pass code.
Likely there are millions who don’t know this and violate in ignorance.
An operable window that can be opened and closed, large enough for a human being to pass through qualifies as an egress window.
I think the plumber was painting a little bit more of a creepy picture than reality. There was an exterior door, window or both. He jsut didn’t see them.