They didn't fail because they've never even been tested. The main issue is the people constantly pushing the "SELF DRIVING CARS WILL BE HERE IN 5 10 15 20 25 30 SOMETIME SOON YEARS!!!!". These things, they take time.
Must have been over twenty years since I've first heard about self-driving cars trials. They do take time indeed and I'm sure I'll never see them in my lifetime, not without a brand new technological approach.
Current neural networks basically
are brand new. They're a very old concept, but large scale GPU computation of neural networks that revolutionized their research only became relatively cheap in 2010s. We're still in the "low hanging fruit" phase of research where small breakthroughs happen pretty regularly. Judging self-driving cars (or any other current neural net applications) on that just because Musk has a big mouth does not make any sense.
AIs usable for game-ready graphics will undoubtedly happen too at some point, it's just a question if there's enough money in it for somebody to do the research and development sometime soon of if we're going to have to wait till somebody else does most of the work on the tech for creating similar but more profitable stuff. Imo even the usability of neural nets for concept art workflow is a huge thing on its own.
Also the tech evolves really fast. Artflow referenced above was launched a year ago and is quite limited, afaik they specialize on portraits and landscapes (which indeed makes it a big surprise they can't make an isometric house), where as Craiyon I think launched like two months ago and is far from state of the art, but it at least already understands what an isometric house is: