This video discusses the major problems that fire fighters encounter with EV fires and demonstrates a new method of efficiently and quickly extinguishing them:

https://www.youtube.com/watch?v=1FWY3LNuPU4

There was a motor accident this arvo in Sydney which included the rollover of a coal-powered car. It started smouldering before the fire brigade arrived and pushed it back on to its wheels. I can't remember the suburb where it happened as there were quite a few mishaps this arvo because of the return of the rain.

I just don't trust these cars. The batteries are a series-parallel affair and the PD is usually somewhere between 10,000 and 20,000 volts, depending on the make and model. The NSW Government is about to stiffen up qualifications for mechanics wanting to work on them too, as a few have received severe electric shocks due to touching live parts. I am assuming that the same will eventually apply across Australia and probably with good reason.

If these battery fire are so readily extinguished with this gear, couldn't the batteries be preplumbed to allow water to be directly injected into the battery?

Water excites lithium-cobalt fires rather than extinguishing them, so no, it wouldn't make the situation better. It is the same as putting water on a magnesium based fire. It'll just get worse. Once the chemical chain reaction in a battery fire ceases, water will help with cooling, but not until then. It is also possible for the battery to flare up again if the water source is removed too early.

Many apartment block body corporates ban the chargeing of electrical vehicles in their basements, not the least because fire engines cannot get in. A shopping centre near me has taken several car charging points out of a basement car park. The industry will need to come up with a solution or permanently lose market.

Fire engine access applys to petrol/diesel cars too, so presumably the fire incidence is less with them.