But they aren't commonly used. It's probably because of medical conservatism coupled with business and status reasons.
And in some cases it does help to have the medical interview with a person. But wouldn't a cheaper nurse armed with a great software tool, offering a 20/30 minutes appointment is better than 7/10 minutes of a doctor's time? In some places in the british system that's what happens and research says the results are comparable to a doctor , with patients being happier.
2. There are crowd sourced solutions like you specify. The one i know is a ycombinator company called crowdmed.com . At least according to the media they do bring something very good to the table, but they're very new so it'll probably some mote time to see how they function and scale.
As an aside, there's an an expert system by a company called isabel healthcare, that in the hands of a regular family physician ,can enable regular physicians to diagnose rare and complex diseases at the level of top diagnosticians.It's available via cloud.I'm sure almost no physician of anybody in this thread will have it.
3. Not sure who is to blame, but i think many of those problems are common globally to some extent. Maybe the british system is somewhat better with the policy of employing lower level providers across many roles.