Is your contention that paying for a service entitles you to zero bugs, ever?

Of course not! But usually, you can quantify metrics for quality, like uptime, lost transactions, response time, throughput etc. Then you can have accountability, and remediate. Even for other bugs, you can often reproduce and show clearly the impact. But in this case, other than internal benchmarks, you cannot really prove it. There is no accountability yet

We already kind of have a solution for this with SLAs. Humans, being (probably) non-deterministic, also fuck up. An expectation of a level of service is, I think, reasonable. It's not "zero mistakes ever", just as it can't be "zero bugs ever".

We're firmly in the realms of 'this thing is kind of smarter / faster at a task compared to me my employees, so I am contracting it to do that task'.

That doesn't mean 'if it fails, no payment'.

But I think it's too analogous to non-tech-products to hide behind a 'no refunds' policy. It's that good - there are consequences for it, I think.

If you paid for a streaming service and the HD option only worked for a random subset of users, and not you, would you complain?

It's a material difference in the product, not just "a bug."