SFO works very well when everyone plays the game right. That means flying the course you are cleared for and maintaining separation that you are responsible for once you are “cleared for the visual.” Or cleared for the FMS visual.
The most formation flying I’ve done is been flying the visual to the 28s in SFO with a 777 on my left side and me keeping station slightly behind to the right. Auto pilot off, auto throttles off. Match speed. Basic airmanship.
ATC relies on the pilots to do as they are cleared. Cathay screwed up several ways. They delayed their base turn, they overshot their course, they failed to slow when they accepted the clearance to follow UAL. ATC did a good job considering that the end result was them breaking off Cathay and sending them around.
United can be forgiven for not responding to the RA immediately for several reasons. They were on short final, inside the bridge and about 3 out. Landing is not when you expect to do a RA maneuver. They heard Cathay acknowledged the speed and maintain visual clearance. They assumed he was complying. They asked tower for advisories on the traffic, they got them.