Makeshift strike plate box

Everywhere I go I check out the door hardware. Usually it's pretty boringly normal, but occasionally there's something fun...

This is a door in a 100+ year old school house that has been converted into office space. My kids take music lessons here. If you look sharply at the above photo, you can see where there was once a piece of vertical trim that has been removed. When they replaced it, I'm guessing, they forgot to take into account the width of the door and the need for the door latch to spring into a box of some sort. When they realized their error, this was their solution (photo of same as above, different angle):

Voila! You take four old strike plates and stack them until they're thick enough to provide a proper box. It's not a high security area, so I guess that while it might not be the best solution, it at least had the virtue of being a cheap solution.