AskCodeMan

Jerry, I just want to confim that plastic laundry utility boxes (used to house drain+water) are NOT allowed in the seperation wall between garage and house.
And, how do plastic electrical boxes or coverplates play a role in this wall?
R302.4.2 Membrane penetrations.

Presuming that this is on the garage side, this is not good, but how 'not good' depends on the answer to the next question.

Question: Does California require actual "fire walls" between a garage and a house, or only separation? Or maybe even something in between the two?

A true fire wall is fire rated from both sides (one example may be 5/8 inch Type X on both sides of the wall, taped, opening protectives, etc. - on both sides of the wall).

Some areas only require the garage/house separation wall to be fire resistant (not truly fire rated) on the garage side (Type X on the garage side only, 1/2" gypsum on the other side, no opening protectives either side, but maybe Type X covering the washer box in your photo as a five sided box around the back side of the washer box).

Other areas, most areas now, do not require Type X on either side of the wall, and thus no opening protectives, however, those areas would require 1/2" gypsum or equivalent on the garage side, which means that plastic box would need a five sided box made from 1/2" gypsum enclosing that plastic box.