They do support them, but right now the fight is just to keep what's there. A few parks have closed due to sale of the land under them. A few years ago San Jose had to enact a moratorium to stop the closures. But that had an expiration date. Since then they've been trying to build a committee of owners and tenants to come up with some solutions to keep the current parks, as well as encourage more.
The fundamental issue for owners is that mobile parks are all under rent control ordinances. At the very least, they want to be able to pass capitol improvement costs to the tenants. As the laws sit now, they can't. So that creates very little motivation for facility improvements, and at a certain point, it's become far more desirable to just sell the land and leave.
Right now, my aunt and grandfather are in a terrible situation. They live in a park that's been sold. The buyers originally offered way less than market value to the tenants, so many have tried to sue, or hold out for a better counter offer. But, they also can't sell to anyone other than the land developer.... And the developer has now rescinded all buying offers. They're literally just waiting for the residents in this senior park to die off. Now, my grandfather has ended up in a nursing home, and my aunt is responsible for two space rents each month. And since eventually they will have to get another place, just taking the credit hit for defaulting could be worse for them.