Level 1 charging overnight on a standard 120V outlet, while not ideal, is surprisingly adequate. Granted, many people rely on street parking or otherwise don't have a parking spot that is right beside their dwelling, but for rented houses or complexes with private garages/parking areas the size of the lift isn't necessarily "get upgraded service and a bunch of 240V EVSE put in".

Same here. Got an EV before we got the proper 7KW charger installed in our house. We had an outdoor socket that the gardeners use for whatever and just have a "granny charger" hooked up to that which I think charges at perhaps 2KW (10A on a 240v UK plug).

We use perhaps 5% battery of our VW ID.3 on a typical day (school run, shops, visiting friends or whatever) so we just do an over-night top-up back to 80% maybe once a week when we get down to ~50%. Working surprisingly well - I am not sure I can be bothered to get the proper charger installed (which is annoying as I have already bought it and the cable for about £800 and its just sitting in my shed!)

None of the apartments I've lived at had a 120V outlet near my parking spot that I could use.

I'll second this. We got a Chevy Bolt a couple of years ago, and I assumed we'd need to install a 240 V EVSE, but it turns out that regular 120 V 12 A charging is totally fine for us. I think there's been one time in the 2.5 years we've had it when we had to go to a nearby fast charger because the battery was getting low.

Of course if you're commuting 2 hours every day, things will be different. But for us, it's been great.

Yeah I’m charging an EV (with a huge battery) at home on 120v and it’s fine 9 out of 10 days.

Certainly that's a factor — but, with quantity 300 parking spaces, it's not exactly the main attraction. Very approximately:

Assuming a 120V / 20A = 2400W circuit (more or less standard in a garage):

100 parking spots = 200A / 24000W; 300 parking spots = 600A / 72000W.

So a distribution line can carry 72kW readily enough — that seems to be about where they are anyways — but if it's carrying that load, it cannot carry any other load, which means that each high-capacity parking garage will need a dedicated line from the nearest substation is.

Then, that parking garage will need to distribute that current to 300 parking spot chargers. Even at 120V/20A, that's 300 new circuit taps; 300 wires, initially. You can use three-phase to reduce that to 100 wires @ 120/20A or equivalent each, which is a lot. Or you can reduce that to 3 wires @ 120V/200A or equivalent, at which point you now have the safety considerations of an outdoor distribution wire in a small enclosed fire-prone space, and you're facing the christmas light problem of "one blown bulb" versus one third of your garage.

Then you need to confront "the chargers need to support burst-mode" so that people can push a button to get a temporary fast-charge ignoring all other concerns — but also "the chargers need to default to trickle-mode", while also considering that trickle-mode should run faster when fewer cars are plugged in (or else tenants will take offense that the chargers aren't using provisioned and available capacity), and that Time-of-Day concerns should cap trickle-mode during peak so that the grid doesn't fail. And that electric vehicles are foreseen as a component of localized grid storage, so garages might need to support backfeeding from cars.

And this all has to be coordinated across three hundred chargers and who knows how many feeder circuits, between one three-phase and three-hundred one-phase, assuming that 72kW (120V/600A) is provisioned to trickle-charge the entire garage each evening at 15A per car max (have to leave some headroom for the burst needs, for momentary overdraw before a charger fuses out a defective vehicle, etc).

This is all doable, but it is logistically expensive, and I would estimate that cost at perhaps tens of millions of dollars at that scale. Doing this for my old 12-apartment complex would merely require 2.4kW of new power delivery, taps, and distribution under the pavement (there's no room for overhead poles to be introduced), without sinking the property into the riverbed it's built on, and without breaking the local emergency services grid that it's drawing from when the creek next door floods every few years.

Retrofit costs are estimated at $5000-$15000 per single parking spot (new buildings are wired more efficiently so halve that cost for anything built since the Model S came out). California at one point was offering a 30% subsidy on retrofits; so, for my example, 300 spots * $5000-$15000 = ~2-4 million dollars (napkin rounded) for a single apartment complex. At local 1-bedroom housing prices, that's around 1000 rent-months of capital investment with no future gain — and that's the most critical part here. The complex cannot recoup that investment through maintenance and usage fees, because those will have to be paid out in actual maintenance and kilowatt-hours — and tenants, in this economy, cannot afford to subsidize the buildout cost.

So until retrofits are either state-funded or state-mandated, landlords have little to no reason to invest their money into the future of electric cars, because they'll get pennies on the dollar at best from their investment. And, given their tendency to collude via RealPage, no one will be the first to build out a 100% EV charging garage because that will not only long-term devalue their other properties without increasing the short-term value of the one improved, but also will start a race to the bottom that they are already colluding to try and prevent.

Yes, trickle-charging is electrically feasible — it's compelling the profitless capital investment that is not.