Yes, it's much more expensive to have two providers. Both in terms of outright costs but even more so in terms of ongoing engineering/technical overhead.

The calculus is how much the expectation downtime is, versus that cost. It's a reasonable calculation and TBH if outages are a few hours once every few years for most cases it's acceptable.

OFC if your hospitals or emergency services depend on a cloud service, you happily fork over the extra money same as you do for any other insurance.