That doesn't solve the issue, because the high rental rates are caused by limited supply due to NIMBYism. If you raise taxes on rental income rental rates will just go up and pass on costs to tenants. Rentals are highly inelastic.

The real solution is to densify and build way, way more. Why doesn't SF look like China with skyscrapers on every block?

Well not sure about SF but Silicon Valley was partly designed low density to keep out Blacks and low-income people. That was a selling point; that's how 1945-1980 suburban American system worked and Santa Clara County was the absolute worst. By the time people were maybe relatively less racist the developers and zoning boards had done the damage.

Edit: it was legal or pseudo-legal until 1964 for developers to subtly (or not so subtly) advertise that their new developments would not be seeded with non-whites. It was a selling point.

Rental rates should always be set at the highest that the renters can afford according to the supply/demand curve. If you raise taxes and rental rates go up, that means they were leaving money on the table previously.

If the rental rates were set correctly, none of the extra taxes can be passed on. The most likely result is the price of the buildings will go down and new renters will be able to buy in more cheaply but get less per rental.

Once again the Land Value Tax shows its brilliance.

Land Value Tax says you tax land at a (high) flat rate per area regardless of value to encourage density. That is entirely different from higher property taxes on landlords (which would not lower rents but might lower property values).

I agree that LVT would make a huge improvement if it was set high enough though. But it will never happen when you have homeowners leveraged up 20x on govt subsidized mortgages who vote for themselves.