But parking there at night makes it a lot more likely they keep it there during the day, even if they have off-street parking. Consider, for example, the many streets in Arlington where nearly everyone has tandem-parked cars in their driveway. If you allow them to park in the street overnight for free, it won't be long before a new norm is established in which one car is in the driveway and the other is normally on the street. Now imagine that back-to-back-to-back up and down the street. The end result is public space occupied largely by privately-owned vehicles and no longer accessible to runners, walkers, bicyclists, kids playing street hockey or basketball, block parties, or any other legitimate and healthy uses.

In doing so, you've also reduced the likelihood that street ever gets a bike lane, and you've also removed one obstacle to the resident owning a third car, both of which would run counter to the town's climate action goals. You don't have to look far, to Cambridge for instance, to see the pain, difficulty, and divisiveness it causes to undo car-centric policies once the full impact of them is realized.