many years ago I had the system worked out for the dodge van we had. Pull the dip stick (no hood lock) slip it through the window seal and flip the latch open on the 3 corner vent window in the door, (no lock button on it) reach in and unlock the door. Then a few times I wanted to drive it without a key so a spare wire could be tied from battery + to ignition wire connection, cross the starter solenoid wires to start, jump in and go. That was a 76 van. But they soon put the key switch on the steering column so it locked the steering when pulled. And added pull latch on the hood. But the 81 dodge truck I still have did not have hood release inside, so I kept a spare key under the hood in the front corner, in a metal magnetic case.
I guess the number code access is the most convenient modern system of easy access, a friend of ours would program it with her home phone number so it was easy to remember for herself and anyone who was acquainted. But several times I've been called on to access a modern car with locked in key. I usually find a way to do it, but it can be difficult. And I'm sure some cars are made so tight it would be impossible without damage. How bout I just fix up an old vehicle so impossible looking no one would even attempt to drive it. Too many unlabeled and miss labeled switches with some that make it do things that make it appear the thing blew out. Buzz smoke and fizzle. I could have some fun with it.