The OP article is a UK paper/website, so I guess they do not realize that Santa Rosa, Oakland, SF, and Lancaster are in four different, non-neighboring, counties. IOW, other than normal people getting frustrated by the mess, actions by the four cities are unrelated.
That said ... sigh ... most of the Joe Rodota Trail (not "Trial" as in the OP article) parallels state hwy 12 between Santa Rosa and Sebastopol (roughly east-west). In Santa Rosa it turn north for 100-150 yards till it ends at the Santa Rosa Creek Trail, which parallels that creek. There are two big problems with having homeless encampments along this trail:
* SR12 is a freeway, and if you think homeless people are too smart to cross sometimes busy freeways, you would be incorrect;
* The trail also connects residential areas, light business areas, and parks; IOW, lots of ways normal people's lives can be messed with and opportunities for property crimes and assaults.
And the USSC just foolishly left in place a 9th Circuit court decision that basically means that if a homeless person lays down on a sidewalk, a trail, or in a park, the city cannot get rid of them unless there is space for them in some sort of shelter.