The front ones don’t seem to be hidden, but yeah - if they’re not meant to be used regularly, people won’t remember them in an emergency. I guess the rear ones are hidden because they probably bypass child-locks.
I don’t know how child-locks work on mechanical door latches. If the vehicle locks when in motion and the child-locks are on I don’t think there are emergency releases on most vehicles? The only ways out would be to get into the front cabin, break the windows, or find the internal boot release.
That is fun, I didn’t know that was a thing. I imagine that roll-overs are more common than submersion in water, but even so, that doesn’t sound like a great trade-off. Even in a crash, being able to quickly jump out the window is good — especially if the vehicle is on fire.