Let's put a few things together.
First, Peter Singer argues that effective altruists should, in most cases, aim to earn as much as possible so that they can give it away to charities that are proven effective in saving and improving lives.
Second, high human capital types are best able to do this when in locations complementary to their human capital. High earners do best when able to live near downtown.
Third, land use policy has made it ridiculously expensive to live close to the downtown of most major cities. Restrictions preventing densification downtown and preventing mid-rises and townhouses in the inner suburbs work to capitalise the productivity benefits of living downtown into land prices, building wealth for those who happened to be there early on. In other words, living downtown so you can earn more mostly gets eaten up by the cost of living downtown. Effective altruists then are less effective than they otherwise could be.
Fourth, land use policies will particularly affect those committed to effective altruism. Those who are committed to minimalistic lifestyles and smaller apartment living will have a tougher time where land use regulations mandate minimum apartment sizes and minimum amenities that some of these altruists would prefer to forgo in order to give more to effective causes.
Finally, one of the most effective national policies for improving global well-being is vastly more open immigration policy. Giving a thousand dollars to a poor person in Africa is incredibly effective. Letting that person move to a place where they can live a better life is even better still. But getting increases in immigration, let alone in refugee numbers, immediately hits onto the "but they'll take our precious scarce houses" constraint.
Conclusion: liberalising land use policies is one of the most effective humanitarian measures a government can put in place. It's a metapolicy allowing other things to work better. Effective altruists can be more effective. We could accommodate more immigrants and refugees. We could make housing costs less burdensome for the domestic poor, reducing pressure to provide them transfers rather than providing transfers to those in greater need abroad. Blocking such liberalisation, because of your particularistic concern for your neighbourhood's character, is the opposite of what humanitarians should do.
Corollary [self-interest watch, though]: Effective altruists might consider supporting organisations helping to liberalise land use policy.*
This will be among the things I plan on discussing with Singer on Monday.
* And here's another good one.