Or just put a pin code on the door
I actually hired a couple of big fords in LA a month or so back, (Expedition, and F150) and both of them did actually have a small num pad on the door, that you can use for keyless entry;
I'd never seen it before, but it seemed like a pretty good idea - convenient, and certainly more secure than having a fob that's endlessly broadcasting an signal that says "open door plz"