Used automotive batteries will be at the end of their life, with only a few hundred more discharge cycles until they've totally degraded.

Again, batteries scaling rapidly still doesn't hold match up with the scale of electricity demand. Again, a day's worth of global electricity consumption is 60,000 GWh. If there's one lesson to take away, it's this: be skeptical of people who talk about "scale" but neglect to actually give figures for that scale.