I think Toyota is being realistic, and prudent. There is a lot of hype around EV's, and perhaps a certain level of ignorance, blissful or willful. On the blissful side of things, you have the average EV consumer who after waiting months for their back-ordered EV will plug the vehicle into the electric grid. Obviously this increases the load on the grid, which entails many things. If the EV owner uses standard household 15/20 amp (120 volt) receptacles, the Toyota charger will use about 11 ~ 12 amps, which obeys the 80/60 rule. Meaning 12 amps is 80% of a 15 amp circuit breaker, or 12 amp is 60% of 20 amp breaker, leaving a little spare capacity on the circuit to hopefully not trip the breaker. If the EV customer upgrades to 240 volt charging, the circuit must use a larger cable, and thus less resistance, and the result is more amperage may flow. So without going into Ohms law, your average Lvl-2 charger will do about 30 amps. Or put another way the circuit is protected by a 37.5 amp breaker, again obeying the 80% electrician "ampacity" rules.

So... just imagine a bunch of homes adding on average 30 amps ambient load to the electrical grid, not all at once, but probably at night, or probably at certain times of day like after rush hour, etc.. So then imagine places like California, or Texas with large populations, and electrical grid capacity issues. In California they have infamous problems with "not in my back yard" problem, unable to expand the electricity grid to meet future expected demand because the various municipalities don't want power lines in their back yards. Also, California's grid is apparently already unsafe, having caused wild fires from old overloaded high-lines, etc. The situation in California is sad because it's probably the most progressive EV market anywhere in the USA. As for Texas, their electrical grid is probably better than in California, but most of the power is from natural gas fired power plants, and there is a second energy grid... the natural gas grid and the quality there is lagging behind. So there is a nexus of causality, and if the NG grid cannot sustain higher load, then the electrical grid beyond will not be capable of delivering the higher demand, etc... and one only has to point towards the winter of 2021, if that implication wasn't apparent already.

All of this ignores the more fundamental issues of mineral extraction, and scarcity. This topic will from an economics perspective act as a natural constraint on EV growth. This may provide enough time for the "grids" to upgrade their capacity, which represents huge regulatory hurdles, and if effectively a mega project in terms of bureaucratic hoops, and actual deployment. So if in an alternate universe we had ample spare lithium, nickle, cobalt, etc... then the constraint would be the speed at which we could upgrade the electrical grid.

One last note about the grid regarding rooftop solar. The grid is not designed for a bunch of homes back-feeding the grid at scale, and there are legitimate safety issues. This is a related issue, in a similar way maybe 1% of homes back-feed solar power, so the grid can absorb the increase for now, but not at scale. Because while we're updating the grid to handle more delivery from power stations, we may as well update the last mile to handle solar rooftop generation. This is perhaps an even more ambitious mega project, as it involves increasing circuit "ampacity" along the last mile, which is like 90% (exaggerating so you get the point) of the total grid cost.