We have that in place. We run phone systems that businesses depend on, and we have SLAs that guarantee this uptime in order to secure customers. We have network engineers dedicated to everything from guaranteeing it on the cloud side to checking Wireshark traces for any hint of abnormalities, every day. When I say 3 people, I mean those of us writing the front-end, back-end, database procs, and code that the open-source libraries require, including forking and custom patches. We have other team members ensuring our HA pairs, load balancing, redundancy, fail-overs, and all the other associated technology is working as expected.
I won't get into the details, but we have not violated our SLAs, ever.
And you'd be surprised at what open-source software we are using to drive parts of this system. Kudos to them, they are helping us maintain this with some rock-solid software.
It can't. It depends on "software services" hosted and coded by "other software companies" so his infra's SLA is basically outsourced to either Amazon, Microsoft or Oracle.
It also depends on an incredible amount of in-house custom code.
If I deploy a change that breaks our Angular front-end, or a C# API change that has a typo that routes calls to the wrong places, or a configuration file for our open-source software that handles the phone systems, how exactly do we tell our thousands of customers they can't run their call centers? Or our restaurant customers can't take orders because their phone systems are dead?
Let's not be ridiculous. I'm not humble-bragging. I'm telling you what I do at my job.
That last one is I suspect what makes it so small scale operators can achieve “5 9s” with a fraction of the engineering of larger operators. You can get a lot of 9s most years because you dodge infrequent risks.