Well, we're probably missing the point, and you probably both know, but I'll continue anyway.
The reason lane sharing is legal in California is because there is not a prohibition against multiple vehicles in the same lane adjacent to each other. The other states, one presumes (since we know it's only legal in CA), specify that vehicles may not drive side-by-side in the same lane.
I'm not sure what CA law has to say about riding between lanes (or, probably more accurately, occupying 2 lanes at the same time which would be what you were doing if your wheels were going right down the line), but all this business is why we call it lane SHARING; in theory, any time spent on the white line is during a lane change (properly signalled, of course, except for those who want to point out that CA state law is pretty vague on whether you even need to signal a lane change).
So the fact that the CHP guideline calls it splitting does nothing to change the legality of splitting versus sharing.
But the motorcycle community typically prefers to call it lane sharing, as that's the circumstance under which it's definitely legal (assuming you are not breaking any other laws at the same time).
And yes, I saw a demo from Google a number of years ago where the car very gracefully handled a motorcycle lane sharing past it.
Your comment matched my understanding from ~10 years ago (from discussions on CA motorcycling forums). However, AB-51 passed last August and it's added "lane splitting" to the vehicle code (which I just found out about 10 minutes ago).
Anecdotally, I'd heard of motorcyclists cited for violating the CA Vehicle Code if they occupy two lanes: "Existing law requires ... that a vehicle be driven as nearly as practical entirely within a single lane and not be moved from the lane until the movement can be made with reasonable safety."
This resulted in the semantic distinction. It's not illegal for two vehicles to share a lane. It is illegal (and still is) to drive in two lanes or to drive "between" the lanes.
Literally every motorcyclist I know here in California calls it lanesplitting or just splittin'. We're not very good at sharing which is why we are riding single person vehicles in the first place.
The reason lane sharing is legal in California is because there is not a prohibition against multiple vehicles in the same lane adjacent to each other. The other states, one presumes (since we know it's only legal in CA), specify that vehicles may not drive side-by-side in the same lane.
I'm not sure what CA law has to say about riding between lanes (or, probably more accurately, occupying 2 lanes at the same time which would be what you were doing if your wheels were going right down the line), but all this business is why we call it lane SHARING; in theory, any time spent on the white line is during a lane change (properly signalled, of course, except for those who want to point out that CA state law is pretty vague on whether you even need to signal a lane change).
So the fact that the CHP guideline calls it splitting does nothing to change the legality of splitting versus sharing.
But the motorcycle community typically prefers to call it lane sharing, as that's the circumstance under which it's definitely legal (assuming you are not breaking any other laws at the same time).
And yes, I saw a demo from Google a number of years ago where the car very gracefully handled a motorcycle lane sharing past it.