I'm curious; what would you have these companies do in such a scenario? If 100% uptime is impossible then what you seem to be suggesting is that people should never use third party services or if they do use them they must not be in a critical path.
Are you suggesting everyone should do everything in house?
If you have to use non-free software, buy software, not services.
If you have to buy services, always have a well-tested fallback path for when that service is not available.
This was in order of preference. If you can, use free software that you can fix and support yourself if need be. If not, buy the software and run it yourself, so you can at least control its operation. The last option is to by SaaS, and if you do, you need to have contingency plans in case it goes away. You should take this risk seriously, and factor it in to your decision when buying SaaS, and invest the engineering resources to make sure you aren't overly dependent on it.
What I'm suggesting is that people should use external services for their lower costs, better performance, or extra features, not to 100% depend on any of them.
There is a popular C# package called Polly that has all sorts of fault tolerant strategies.
https://github.com/App-vNext/Polly/wiki/Transient-fault-hand...
In this case, use a Fallback strategy that responds to an API failure with some type of generic success response.