I see spelling mistakes all of the time in print media, and they've had spellcheck for 30+ years.
I can see how "Redwood City" could become "City of Redwood", and then just "Redwood", through multiple steps. I had never heard of it before moving to norcal.
Neil Young, who lives nearby, called it simply "Redwood" in 1972's hit Heart of Gold. (I've been to Hollywood; I've been to Redwood.)
It's been fixed now.
Do human editors catch every mistake? No.
But a news site (SFGate) that purports to be local to the area should know the name of the county seat of one of the Bay Area counties.
I feel ridiculous having to explain this, but it's possible to know the name of a place and still get it wrong when you intend to write it down, or overlook a mistake when reading it over.