[bufordsharkley]

Let's say that your town is considering whether to preserve a zoning policy of all single family homes with a large minimum lot size, or is looking to allow density. What would prevent you from supporting the lower-density option?

One reason may be that you are concerned that restricting the development of land would drive scarcity, leading land values to rise (which would cause your property tax to rise). You're effectively forced to pay for the cost of rising land prices.

...Now, if you are sheltered from rising land values, as per Prop 13, you now suffer no repercussions from a downzoning, and in fact may be completely indifferent to how the land market is behaving. Many homeowners are now free to act in their own best interest (which means downzoning), instead of being incentivized to create capacity for more housing.