I think that when the voting period begins, the NAPs are just randomly selected from whatever is possible in that neighbourhood (in certain Evergreen Harbor neighbourhoods, extra NAPs specific to Evergreen Harbor are possible, like the ones that encourage modern development or clean up the trash).
There's always an extra free slot where the player can add their own suggestion for people to vote on if the NAP they wanted isn't in the randomly chosen bunch. Then they can dump all their influence in to that or encourage other sims to vote for it to make sure it wins.
When Eco Lifestyle came out, that's basically what I did when it first activated in my game, switching between all my played sims in every neighbourhood to make sure things I wanted were being voted in. After four weeks, the four NAPs for each neighbourhood will then all be in place and will stay that way until the player makes a petition to change them.
If you have any households placed in a neighbourhood the moment Eco Lifestyle is added, then NAP voting happens, even if you don't play there. For example, even if you don't play Brent or Brant Hecking in their neighbourhood in Brindleton Bay, after four weeks if you visit them, or just go to the vet or pup park, then you'll find four random NAPs active there.
If there's an neighbourhood with no living residents, then there won't be any NAPs until a household moves there, for example the unspoilt Mua Pelam island in Island Living which starts with no sims living there.
For neighbourhoods like Magnolia Promenade, I had a sim who owned a business there, and I think that triggered NAP selection to take place, even though no households lived there, it's like the game treated the owned business and my sims owning it as a trigger, even though I had no power to vote in that neighbourhood.
After years of having Eco Lifestyle, I'm pretty much satisfied with all the NAPs active in every part of my sims world. I only have to keep an eye out when new packs come with a new world to check that no undesirable NAPs get voted in, like the paper bags on head one. Once you've picked four NAPs you like, then it will stay that way forever until you change it.
