I've only lived in Los Angeles and California for 6 years, but maybe I can provide some perspective.
The first important thing to keep in mind is that any state or local spending must be voted on and approved by a ballot measure. California has a lot of "cash", but money raised through taxes can only be spent on what it is allocated for, which effectively ties the hands of elected officials. It is very easy for special interests groups with a lot of cash (such as corporations) to buy votes using public scare ads. This means that a lot of ballot measures get extremely watered down to please everyone, making them incredibly ineffective.... And often results in huge wastes of spending.
Second, incredibly strict building code and zoning laws have been hijacked by NIMBYs and Republicans to stall out construction of high density housing and increased transportation, by scaring everyone with the fear that it will lower their property values and invite undesirables (poor people) to their neighborhoods. Routinely all legislation to fix this at the state level has been stopped because Republicans still hold enough power to kill bills in process, because it's very easy to kill bills long before they reach the floor in California. Trying to keep Republicans and Democrats in particularly purple districts on board generally involves including measures meant to sabotage the bill even if it did pass.
Lastly, California has several disastrous laws that were put in place by Republicans back when they ran the state, that can only be removed by ballot measures and are widely still popular among the public. The chief culprit is 1978's prop 13, which effectively locks in commercial and residential property taxes at the rate they were evaluated at the year of purchase. This effectively is a poor and youth tax, where new property owners, who generally are young and have less wealth, take on a larger tax burden. But that's not even it's worst aspect. The biggest problem with prop 13 is that it encourages older people (in this case boomers) to not move, because buying a smaller retirement home would have a higher tax cost or because they intended to transfer their home to their children when they pass away. Kids can inherit the lower tax rate in California. This has effectively killed the natural life cycle of home ownership, and there are a lot of elderly people living in large homes that really would be better served by a young family with several kids.
What I think surprises a lot of people is that California is not as liberal as political opponents from out of state typically claim in their rhetoric. California has a lot of social liberals who are economically very conservative. People who own homes may know their property value is bloated, and they hate to see all the homelessness, but they don't want any solution that could correct THEIR property's value. It's incredibly selfish, because any real solution to address the California housing crisis is gonna lower property values. It's the whole "well, I got mine" attitude that makes people complacent.
It's also worth pointing out too, that because of California's nice weather, a lot of homeless choose to live outside or in their cars. Living in a shelter often risks giving up everything you own, and many people choose the sidewalk tent over a bed in a shelter.
That being said, I've lived in California for 6 years, and it's way nicer than where I grew up in the Midwest. Sure, I see the occasional homeless person, but I saw that too back in Indiana. What people don't realize is that Los Angeles is HUGE. The vast majority of it does not look like those videos at all.