They blame techies for the hike of real-estate price,
  [...] they also oppose any construction of high density
  accommodation

My theory is there are three parties in this discussion.

Renter Roy can't afford a house, and thinks tech companies' money is bidding up prices. Homeowner Harold has lived and worked in this neighbourhood for 40 years and doesn't want its character to change and his house's value to fall. Techie Tammy wants somewhere to live, she'd prefer not to spend a fortune to live in a hovel while her neighbours shame her for gentrifying.

Any pair of Roy, Harold and Tammy can get on OK - but it's just not possible for all three of them to get what they want.

There seems to be a contradiction - but that's because any time Roy and Tammy are about to agree, Harold is motivated to enter the conversation and disagree - and the same thing happens when Harold and Tammy are about to agree.

Actually, does Harold ever agree with either party? Tammy and Roy both want low housing costs, and Harold doesn't.

Sure, you can get to an armistice with Harold and Tammy: Housing costs are high but your salary is such that even spending 66% of your pay on housing leaves you with an ample amount of money.

But I wouldn't call that agreement anything other than begrudging.

> Actually, does Harold ever agree with either party? Tammy and Roy both want low housing costs, and Harold doesn't.

This seems like the essential problem. Harold isn't actually a buyer in the housing market; he locked in a fixed-rate mortgage 20 years ago. If he's planning on retiring somewhere outside the city, or to a managed community, he might never be on the buyer's side of the market again.

But he's definitely a seller - that house will presumably be sold or passed on to his kids. Property taxes are a pain, but they're a manageable one for a house bought as an investment. Harold is actively opposed to Roy and Tammy; if their rent doubled that would be a good outcome for him.

We keep treating this like all the residents of the city are a group, but that's not true. Renters own zero units of housing, homeowners own one unit, landlords own multiple. It's not at all guaranteed that homeowners align with renters more than with landlords.

There is a limit to the extent which the higher property taxes are tolerable and most people aren't really investors. However, as I understand it (I am on the East Coast), in California's case your property tax is actually locked in at the time of purchase regardless of appreciation.

Seems like only Bay Area homeowners lose out if big tech companies decide to stop colocating all their workers in a handful of zip codes. And they won't get much of a say in that case.

The execs like the Bay Area..

Good point. There's more to the preferences of executives than they might care to acknowledge.

> Any pair of Roy, Harold and Tammy can get on OK - but it's just not possible for all three of them to get what they want.

But this is a dilemma (or in this case a trilemma) only for individuals, "don't change the nature of this neighbourhood" shouldn't be something policymakers care about.

> "don't change the nature of this neighbourhood" shouldn't be something policymakers care about.

Who do you think votes for those policymakers? (And donates to their campaigns)

While there are people who oppose high-density construction in general, the writer of this article isn't necessarily among them. There's a difference between the arguments "we shouldn't build high-density housing" and "having employees' housing, shopping, and most of their other needs provided by their employer has lead to some bad things in the past".