Are there any cars that let the driver turn on/off rear door child safety locks electronically from inside the car? That is,by pressing a button instead of opening the back doors and manually flipping a lever.
I think James Bond had one of those!
Seriously, I can’t think of any. I can’t figure out what the benefit would be since you have to open the door to get in anyway.
Sometimes there are adults riding in the back and it would be nice to press a button to let them out. 
Well, I know that this is stating the obvious, but I will do so anyway:
When you have adults riding in the back seat, try to remember to deactivate the child locks when you open the back doors to let them into the car. Yes, it is inconvenient, but that is the only way to do it if you want to avoid “trapping” them in the back seat, so to speak.
I believe on both our cars ford and chevy unlock from the driver control even if child locks are on. I’d have to double check ours if you need but give it a try, try hitting it twice if once does not work.
Waterboy, that will unlock the doors so they can be opened from the outside, but it won’t disable the child locks, which prevent the rear doors from being opened from the inside, whether or not they are locked.
VDCdriver has explained it well, and it seems obvious to me too. Since adult passengers have to open the doors to get in, while they are open, go ahead and either disable the child locks yourself or tell your adult passengers to do so. You can kill two birds with one stone while the doors are open.
What’s next? Do you want the driver to have a button that will unfasten the passengers’ seat belts for them? I think this is unnecessary, and if you forget to press the button to re-lock the child safety locks, you would defeat their purpose. Making you get out of the car to turn them on or off forces you to pay more attention to them than you might otherwise.