The Collective Action Problem. Locals have a concentrated interest in preventing development. The broader public's interest in there being housing outweighs that, but it's diffuse. You see the same thing play out over and over again in cities around the world: it's so much easier to organize opposition to housing than support that no housing gets built.

Developer: "Hi neighbor, would you like me to build a house so that someone can live in it? Do keep in mind that it would increase housing supply in your area, thus increasing supply and putting downward pressure on your property's value. That okay?"

Neighbor: "No, thank you!"

Because "local issues" aren't just local issues, as much as NIMBYs hope to frame it that way for persuasion purposes. There are larger global effects. In this case, a crippling housing crisis, leading to disenfranchisement and alienation of large swathes of the populace, leading to human suffering, inequality, and political extremism.

You end up with people trying to optimize for their own personal well-being at a micro level leading to an untenable macro-level situation.

Nothing, so long as their decisions don't abridge other fundamental rights. I can't speak to Ireland, but we've pretty clearly in the U.S. created a regime that fundamentally violates foundational principles of private property.

There isn’t enough housing. To solve this we must do some of the following:

- Increase density of living in existing stock (no more solo pensioners living in mansions)

- Increase housing stock

This will have to impact someone, somewhere. All locals will say no so the problem will not get solved by local groups.

More fair is that there is a process by which the impact is spread somewhat evenly and extreme impact is avoided entirely.

This cannot be coordinated by locals because they have no incentive to take on any of the burden.

They profit by blocking other people from becoming locals.

The problem is which locals end up being those that dominate the deciding.

What we've seen happen over the decades is that those with the most amount of time and money available end up drowning out the voices of others, as they have more time to devote.

So inevitably older, wealthy, established interests end up dominating the discussion as younger, marginalized, working class people are too busy just trying to get by to engage in local planning.

Accordingly the local consultative process ends up favouring the older wealthy and established land owning locals and not the marginalized working renter class locals.

I actually support that. That's why I think someone local to a plot of land is the person who should decide what to build there.

That's a separate question. But I think all evidences points to that NOT solving any housing crises.