It's harder in the exact way that AI is good at, though. You need to slog through very large amounts of boilerplate until you find what you're looking for.

It's not really more complex once you're practiced at it, just tedious.

You might have noticed throwing billions around has diminishing returns

Much harder than fixing from source, but much much much easier than making a bug report that Microsoft / Apple / etc will care about. You get better results from a wishing well than Apple Radar.

Eh, there's a huge difference between having AI fix a bug and fixing a bug.

The latter implies that you've understood where and how it happens as well as noticed any other areas that may be impacted by fixing the bug or by not fixing it. AI just fixes it without thinking about anything else - which is great, but it explains why serious people (and Microsoft) aren't doing just that. We've spent decades worrying about quality, reliability and performance. Using AI is saying all of that was poppycock and it's faster to rebuild than to understand and fix. It's a different school of thought, and hopefully one that bursts down in flame in a few months.