What exactly is the purpose of population signs

Because I clearly don't understand them. I'm driving Megan, my youngest step-daughter to Drivers Ed today and I noticed the population sign. Can someone actually tell me why the hell they exist in the first place, and who the dumb ass is that actually has that as their job. Not to mention how much a state actually pays to not only buy the sign, but to keep it updated. Then, Megan, made an assumption that it has to be updated yearly, especially since people move in and out of a town so often. Still, who really gives a shit. Not me, and I'm certain it's not exactly the topic at the dinner table. If it is in your household, you must be pretty damn boring.

After trying to wrap my head around the concept of these signs, the more I thought about how many there are for each town here in California. You can pretty much enter and exit each town border with multiple streets. Does this mean there is a sign at each entry and exit, because that would be an even bigger waste of money? I'm starting to think we should just do a way with them altogether, and start trying to put the money toward a better cause, like education perhaps. Then again, I'm not the Governor of California, but maybe I should be with my bright idea on saving.