This is the crux. Sure, for high level software (e.g. Web apps), many parts of the system will feel like black boxes, but low-level software does not generally have this problem. Sure, sometimes you have to deal with a binary blob driver, but more often than not you're in control of or and to debug most all of the software running on your system.

> Building a bridge

There should NOT be significant unknowns when you're building a bridge, this is how people die. You turn those parameters into "knowns with high confidence", which is not something you can even begin to do for the LLM parameters described above.

In absolutely every way that matters and in all the details that don't matter.

> Do you know everything in advance about the composition of terrain, the traffic, the wind and the earthquakes?

No, and there are established procedures and ways to establish those facts.

"This magical incantation that I pretend works better because the US is asleep and more compute is available" is not such a procedure.