A decent L2 charger should be installable at scale for ~$1K per unit IMHO. I'm basing this on the fact that a singular L2 home charger can be installed for about that. Figure the industrial variant costs a little more, but you get savings from the mass scale of deployment. They probably cost more now, but competition will bring it down as we scale.

Also, not everyone will even need L2 everywhere all the time, because many will be able to charge at home or use fast-chargers in emergencies. You don't have to be near-full at all times. You could deploy them at only 1/N spots, say something closer to 1/4 of all the spots, if even that (apartments might need 1/1, but streets and business parking lots/garages would need far less. You don't need them in any short-term street parking areas, as L2 is mostly-useless unless the car is sitting in place for hours).

You also don't necessarily need to have the raw power to run them all simultaneously: you can have local groups powershare (e.g. deploy 8 chargers with a feed-in that supports 4, and the chargers can coordinate to drop their charge rate as more people plug in).

If those wild assumptions are true ($1k, 1/4 of parking spots), LA's bill drops to $1.5B, which seems much more reasonable. The capacity will build up organically over time as EV adoption grows, starting with corporate and apartment parking lots.

I think in this hypothetical all-EV future, there would be other compensating changes to the city as well. Like, all gas stations would go poof, and their tanks, and the fuel delivery trucks, and most of the refineries, and all of the associated impacts on peoples' health from both the fueling and the car exhausts, etc. There's a lot of potential upside to offset any reasonable electrification costs.