This is of course not limited to cars or even this type of key fob, but instead, anything that uses transmitter power as a proxy for distance/proximity, and tha

This is of course not limited to cars or even this type of key fob, but instead, anything that uses transmitter power as a proxy for distance/proximity, and that transmitter power has any chance of being signal boosted within reasonable means. The only true solution is to stop using transmitter power as a proxy for proximity when houses/etc are not opaque to that signal. Instead, use something that the house is effectively opaque to for the distance part of it. IE include an ultrasonic receiver in the keyfob, transmitter in the car and require it output the distance to the car. (or something, i'm just spitballing) The problem is almost certainly the power requirement.