In any case, luma noise is not at all a massive issue, and it is a mistake to say that crews do their best to produce a noise-free image. They do their best to produce an image that they want to see, and some amount of luma noise is not a deal-breaker. There are routinely higher priorities that will take over using the lowest ISO possible. They can also be financial considerations, if you don’t have enough lights.

It is only an issue in content delivery.