Video of a cop rescuing a woman from a car with an underhood fire was on TV in the last day or two. He had to break the window with his baton to drag her out of the car. The voiceover said the woman could not open the doors. Neither could the cop apparently so he had to pull her out through the window.
I know most newer cars have automatic electric door locking as soon as they start moving. If electric power is cut, as could have happened with the fire, would the doors remain locked?
There are far too many different type of locks to speak for every vehicle, but I’ve been in a large number of different vehicles and all of them had a manual way to unlock the door from the inside. Panic can make people stupid, and/or some people simply don’t pay attention to the details (like where the manual lock on the car is located). Lastly, a large number of vehicles I’ve been in will unlock just by pulling the inside door handle. While I can’t say for sure that it is not battery-assisted, most (if not all) of the ones I’ve noticed worked even when the engine and battery are off.
ETA: If the cause of the fire was an accident, it is possible the door was jammed and even unlocking it would not have allowed it to be opened.
I think I may have heard of one or two models of cars that didn’t have an actual physical lock/unlock latch inside the car that would work even without power, but in general there’s a way to manually unlock the doors. However, even if you can’t, it’s not that much different than child proof back doors.
Keep in mind, most people don’t manually unlock their doors. That and panicking because their car is on first may have made it more difficult to find the latch (for the first time) and faster for the cop to break the window instead of just waiting to see what what would happen.