Ride sharing services give you the speed of driving without having to park, so lots of people will use them until they cause enough congestion to make them as slow as public transport.
The central subway LRV is mostly for tourists, and while the third street and central subway lines were, together, partly intended to help shuttle people from the SE to Chinatown, as of now the Chinese community still oppose it. Everybody knows why they oppose (it just can't be said aloud[1]), but personal convenience usually trumps anti-social community sentiments. Once it opens I guess we'll see. If opposition quickly goes away then that would suggest it's more convenient than the existing heavily trafficked express buses, but somehow I doubt that will happen.
What would be a meaningful addition to the network is if they finally extended the E-Embarcadero (sister to the F line that opened in 2016) to the Marina, using the Fort Mason tunnel. But crime in Fisherman's Wharf is way up, so I suspect it's being quietly stalled by Marina activists.
In any event, LRVs suck, the F- and E-lines notwithstanding. They're slower than buses and 10x as expensive, in SF and most every other American city.[2] Oppose LRVs! All they do is give public transit a bad name. It's right-of-way or no way, but preferably grade separated.
[1] It's the same reason the North Beach and Fisherman's Wharf communities successfully stopped its extension past Chinatown.
[2] I think the only LRV I've been on outside the U.S. is Vienna, but it was mostly historic. Somehow it seems historic routes see less competing traffic, perhaps because they were built in a time and place that doesn't permit much car traffic to begin with. I've been on BRTs in Guadalajara and Quito--if you can't grade separate but can acquire a right-of-way, LRVs seem like a waste of money. They're even a worse waste of money if they don't get unimpeded right-of-way.
The killer is sharing lanes and traffic lights with single people driving cars, or even worse with double-parked Uber taxis.
Re: [2] I think LRVs work when they complement a subway/commuter rail ala U-bahn, S-bahn. But I think your observation is right, they’re often in settings where they don’t need to be fast. (Serving an inner core).
It's hard to dispute their fears. Considering the profile of crime in SF, especially property crime, they're warranted. This is more true today than when they killed the extension.
Of course, the proper response is to address the underlying problems; to stop the self-perpetuating cycle. But that's intractable in the short-term. Alternatively, the city could just beef up crime enforcement so that we can all enjoy better transit, which is itself a small (tiny) step in dealing with the deeper problems. But we're too busy enabling street addicts and pandering to extremist progressive fear mongers (e.g. anti-vaping, etc). It's difficult to blame anyone for not trusting the city to maintain law & order.
If you’re thinking of San Francisco: how has public transit grown in the past 20 years? What new lines have been built? Sure, the cost of living has gone up, but has the total area well serviced by public transit increased? That indicates to me SF does not favor public transit as policy.