The linked article directly talks about this, at this level of downtime customers are promised a 50% discount. That's what the SLA means, effectively

Cars warranties are also aspirational/virtue signaling, to a point.

If the maintenance costs exceed the margins on the cars you lose money. Do that on too many product lines for too often and you’re looking at bankruptcy. But some makers clearly are more risk averse than others, so a 6 year warranty from maker X does not translate to a 7 year warranty from maker Y.

But Atlassian's (published*) SLA offers a credit of at most 50% of the month.. not really the same as a manufacturer warranty on a car, which the costs of servicing could easily exceed the price paid for the car.

* - their larger customers will have negotiated SLAs.

edit: to be clear, I expect Atlassian will offer concessions beyond their SLA obligations. I'm only responding to the comparison.