I spent 25 years there and didn't see too many of those. Then again they don't really like to be seen. I wouldn't call it a nuisance though? They aren't an overwhelming threat, just a minor nuisance.
Bay Area - especially Palo Alto and San Jose - I’ve seen rats the size of small cats. And had to remediate multiple houses where they got into it and made a huge mess.
They’re fruit rats that like to live in trees so it’s pretty rare for them to make it inside the house - I’ve only had one rat make it into the walls in 20 years of living in a 100 year old house despite a dozen fruit trees surrounding the property. I’m in LA though so maybe the Bay Area winters drive them inside more often.
They absolutely ruin the harvest though. We manage to pick maybe a tenth of the pomelos and pomegranates that ripen before the rats get to them. I made a deal with one of my neighbors to tear down the fence and hedges separating our properties to prevent them from easily moving between trees on that side so at least the avocados are safe.
We’ve got rats in California but they’re a minor suburban nuisance, not a giant public health problem like in New York.
Only in areas with fruit trees though.