To be clear, in Aus we don't have 99% reliability. It's about 45 min every 2 years (whatever that works out to). That number was to explain the cost savings.
In much of the world those cost saving are directly applicable. Most of the world's population doesn't have 99% reliable electricity, and so they build reliability at the edges with everything from batteries in phone towers, to batteries in lighting.
It isn't at all clear to me if this is more or less expensive for new infrastructure. Given the increasing popularity of roof-top solar, the pricing model for 24/7 reliable wiring doesn't work out now in places where it is already built out. Network operators are trying various legislative measures to get subsidies for the networks, because no one wants to pay the rates they cost to maintain.
If I had free (or very cheap) electricity 99% of the time, spending $5K to get 99.99% reliability via a battery system is very tempting (and we are getting close to that point now). $1K for 99.9% - maybe.
One interesting thing is that the distribution of the downtime matters.