Here is an example of a recently programmed car key. This is a smart (aka proximity) key for a 2018 Mitsubishi. Because this type don’t have to be put into the ignition to start the car, they do seem to get lost more easily. It isn’t unheard of for people to put them on the roof of the car then drive off.
Always remember that proximity keys can render your car vulnerable to theft. A criminal doesn’t need to have your key physically in his hand to start your vehicle. If they can detect your key inside they house, they can simply relay the signal to the car. Always leave the keys at the opposite end of the house to the car. Or put them in a suitable RF blocking sleeve or metal box.