Are you sure this isn't just 'turnout inertia' working in your favor? People who are relatively content with the zoning rules are probably not actively engaged on the issue. But swap them in a way that they become unhappy with (as you presumably were) and you see sharply increased turnout in the opposite direction.

Put another way, one of the historical critiques of democracy was that it ends up catering to interest groups whose interest may not align with the rest of society. At first that seems paradoxical, because a more knee-jerk critique would expect democracy to just turn into a tyranny of the majority. But the reality is that people generally don't act on things until they are sufficiently incentivized to do so. And that incentivization is often reactive in nature.