Probably plexiglass. Pretty common as a safety precaution.
When my little sis was about 7yrs old, she accidentally put her arm through a glass window on my Grandma’s storm door. She could have very easily bled to death. Fortunately, through good first aid, and a quick trip to the hospital, the only lasting effect she has today is a nasty scar on her wrist.
Grandpa replaced the window (and all the other low windows) with plexiglass, to keep from ever happening again.
So from my own personal experience I would be more concerned with keeping the glass from breaking than from being trapped inside. A good kick can take the entire pane of plexi out without breaking it into shards. IMHO the plexi is a good thing.
(On a negative note, it does scratch up fairly easily, and it looks bad after a couple of years.)
Those particular areas of glass should be of tempered or safety glass as recommended in the IRC R308.4 Hazardous locations.
If the window or door is made for emergency egress, it should not be aticipated that the glass needs to be broken, it is assumed it will be operable.
Plexi-glass can also be very flexable an prone to push right out of the glazing,
depending on the situation.
The only place I expect to see it is on Ghetto vestibule doors.
I would not call it acceptable on a regular window.Tempered glass may be required as stated above.
Approved plastics that meet the ANSI Z97.1
Standard are another form of safety glazing.
Limitations on its acceptable use arise from
fire resistance ratings. In garages, inspectors
may find that original glass panels in exterior
passage doors have been replaced with
plastic. While it may provide safety, a
disadvantage of plastic is that it easily
becomes permanently scratched. Plastic is
often used in skylights.