"No, "all" the local news broadcasts did not do this. At the time there were 4 local news broadcasts (with 44 trying something briefly). KTVU and KRON did very serious newscasts with no sensationalism. KPIX was straightforward but a little less serious. But KGO-TV under Van Amburg was the genesis of the entire "happy news" concept. It started there, became a hit there, and spread across the country. KRON, KPIX, and KTVU, however, kept to their more serious styles and did not try to emulate KGO-TV. Lloyd Lindsay Young would have never landed a job on the other 3 stations, for instance."
Well, maybe we're splitting hairs a little - as I said, News Scene and Van did it better, but I have to disagree that the other channels were bastions of real journalism. KTVU was the first to drop the sensationalism and "happy talk" in the late 70s - but Channel 2 Action News in the early and mid 70s was very different than what the 10 O'Clock News became.
I remember that Amburg's ratings finally started to wane when KPIX brought in Dave McElhatton. McElhatton was considered a stand-up guy, so I'm not putting him down, but KPIX in that era fit the definition of "happy talk," and also became very adept at the sensationalistic tease. KRON tended to flop around without any consistent identity or direction, changing anchors like most people change their underwear - until around the time they hired Pete Wilson, but that was much later.
And all of the 3 network affiliates competed with each other with lurid sweeps months "special reports." Remember those? The subjects of those exposes was generally lurid sex, violence, pornography, or something equally prurient.
Channel 7 was not the only one that played that game. The only exception from that era I can think of was KQED's daily local broadcast. I believe they called it Newsroom. That was real journalism.