>Re-zoning only works if there are developers who want to redevelop the land.
Developers very obviously want to redevelop the vast majority of LA. The marginal cost of a housing unit is vastly higher than the cost of building that unit. To raise long-term tax revenues, LA could not just legalize redevelopment. They could actually incentivize it.
>For existing neighborhoods this means buying dozens of SFH from people who don't want to move.
The people living in SFH don't want to move exactly because they're not generating enough tax revenue to keep the city afloat (mostly due to Prop 13). Eventually the city will start having to raise taxes very dramatically or declare bankruptcy. That's the entire message from Strong Towns.
The more we put it off, the bigger the impact will be. When your city is effectively long-run insolvent, but you have the ability to change that even if it's politically unpopular (and LA does), then it's "trivially" doable, it's just that people don't want to.
That's not the case in many other cities.
In other cities demand isn't there. People will just leave when taxes go up, and the town will declare bankruptcy. At that point, they will effectively lose most of their population, or people will just live without things like clean water. An example of this happening is Jackson Mississippi, where the water system failed, and the city didn't have the money to fix it. The ultimate solution was just a federal bailout, which is not sustainable if these types of crises become endemic: https://en.wikipedia.org/wiki/Jackson,_Mississippi_water_cri...