Our fire department also does drives where they sell green reflective house numbers, pretty much at cost to anyone who wants one. They go right below the mailbox and are double sided. If you are going to enact an ordinance--make sure you do it right. There are a few things I have found that aren't helpful:
1) House numbers on one side only--this is really unhelpful when coming from the other side!
2) House numbers that are spelled out (ex. three thousand five hundred sixty four) I've missed many houses because in reading number quickly I just didn't translate the words to numbers correctly.
3) I would say that if it were in some uniform place, like on a mailbox, that would be more beneficial than having it on their home. While mailboxes can also be obscured by trees and bushes, a number on a home is much more likely to be obscured, and if not lit, are impossible to read at night
4) they should be reflective. I know that some people are against the reflective green on their mailboxes, but if everyone has them, it actually looks uniform and not all that bad!
5) some ordinances have street numbers on curbs--once again, not a bad second choice, especially if people are against the reflective numbers on their mailbox, but also slightly harder to read
Keep in mind that if you give people anecdotes on people not having easy to read numbers, and the consequences that came with it, you will likely have high participation. You will always have the anti-government types that will want to say, "YOU can't tell ME what I have to have on MY house" so it's a lot easier when everyone is working together and they do it of their own accord. You could even have a drive where over the course of a few weeks, when you have cars on patrol, they stop at every house that doesn't have numbers to inform them of the hazards of not doing such (they do this once in a while in our area but compliance is also really high already so it's not like they are stopping every third house)
We have on many occasions been asked, "what took you guys so long?" We very unapologeticaly inform them we were unable to find their house due to no numbers. That is usually a wake up call (though sometimes one that comes a few minutes too late).
One more complicating factor we have in some part of my rural department's run district: the numbers are not sequential. Now I'm not talking we change municipalities and all of a sudden we jump from 3000's to 8000's. I'm talking we go down a street and the numbers on one side are 8002, 8004, 8006, 8064, 8012, 8014, 8016, 8142, 8016... This is just due to the way things were done historically. Fortunately we have parcel maps on our computer to deal with things like this, but if the computer is down, and we can't find your house after doing a pass between the given cross streets, we tell dispatch the number doesn't exist and mark back in service. (The reason numbers are important here is that when we can't find a number, we go between the given cross-streets in the dispatch and look at each number until we find the right one, even if we already have blown past where it should be sequentially. But if there are no numbers, then we won't know which house it is.)
Also, something we learned from experience: The fire department during their first drive also included installation for free and one of the volunteers would drive out and actually install the number placard on your mailbox. At least that was the idea. We never offered to do that again. Why? The volunteers had a lot of trouble locating the houses on which they were to install numbers... :huh: I don't know why no one thought of that beforehand...
