Canada

I don't understand. Zoning is determined at the municipal level, not decided by the people who own the lot

This is more specific to municipal amalgamations. For example a mid-density multi-use neighborhood rakes in a lot of cash and dumps a fair amount cash into amalgamation budgets. It also has relatively lower infrastructure spending.

That cash then needs to flow into single family neighborhoods/burroughs/cities. These areas generally pay lower property taxes because they are less dense; but also has higher maintenance costs for the more spread out infrastructure. Plus and additional infrastructure cost of the residents traveling to other neighborhoods/burroughs/cities

So I'm suggesting that amalgamations, or even provinces, should be slapping an additional tax on municipalities that are allowing single family zoning.

The people that own the lots will now be more in favour of allowing/voting for denser and mixed used zoning to reduce their property taxes. Some won't, and that's okay, since they'll at least start carrying their own burden.

It's like Land Tax Lite, and a good early early move toward more LVT taxation systems in the future.

People need to be able to buy their daily necessities within walking distance if we want to reduce the amount of traffic, noise and pollution in our streets.

I'm right there with you. We should be charging the premium to live in car dependent places and subsidizing walkable and transitable areas. Rather than the inverse we do now.