[trimtab]

Existing stakeholders see more traffic, less parking, more noise and disturbance. Higher density housing generally creates more conflicts among residents.

So existing residents already in place resist more residents arriving in the same area. Which is understandable, since ADUs do not address adding services provided by government to existing properties. They just increase the number of inhabitants in the same area.

Also much of Portland has a much better and less expensive public transportation system than the SF Bay Area does.

[everybodyknows]

All true, yet here in Mountain View where I live, a rent-control ordinance was just passed. This might have been averted by promotion of an ADU housing supply and concomitant reduction of rent increase pressure, by mediation of a more-or-less open market.

Instead, Mountain View will have occult "markets", dealing in favors and claims of personal need.

One should always choose the lesser of two weevils.

[ianbicking]

Few cities have recovered their 1950 population, and the number of people per square foot of residence only keeps going down. I'm not sure this represents an increase in density.

[simonbyrne]

Is this really correct though? If increasing the supply of housing allows people to live closer to heir jobs or other amenities, wouldn't that decrease traffic?

[sokoloff]

On my particular side street (right on the edge of Cambridge, MA)? No; on a hyper-local level, it will increase traffic and parking pressure.

Via induced-demand, it might even make things worse within the city center.

People vote based on their hyper-local experience and fears. NIMINBY ("not in my immediate neighbor's backyard") is not entirely irrational here.