Hi, plus codes founder here. We did think about this but we think there are two things that reduce the impact of this kind of movement.
First, most plates move a couple of centimeters per year, and the fastest plates (those in Australia) move around 7-10 cm. The default precision plus code is 13x13 meters, so it should take a long time to be wrong.
Secondly, one aim is for this to be an addressing solution in places without street names. If the point doesn't exactly align with the house, if they have a sign, it's still going to be easy to get the right place.
First, most plates move a couple of centimeters per year, and the fastest plates (those in Australia) move around 7-10 cm. The default precision plus code is 13x13 meters, so it should take a long time to be wrong.
Secondly, one aim is for this to be an addressing solution in places without street names. If the point doesn't exactly align with the house, if they have a sign, it's still going to be easy to get the right place.
Nice question though!
[edit: move corrected to most]