There are at least several options which are already in use:
Class observation
Syllabus evaluation
Assessment evaluation (i.e. looking at their exams, quizzes, paper writing rubrics, group projects, etc.)
Student interviews
Independent student assessment (get a random of sample of the teacher's students and see if they've met the course objectives)
You can check this out if you're interested in evaluating for learning and teaching efficacy.
I worked at (and continue to maintain close relationships with people who work at) a highly respected American university. The American higher education system is a train wreck. It's comically overpriced, systemic accountability issues result in sub-par curriculum, and mismatched incentive systems result in a higher focus on "research" than academics. There was literally a professor at my university who was so incompetent that she stopped showing up to class, had a student TA teach the class, and wouldn't even help grade papers because "she didn't know the material well enough." Complaints were brought to the department chair year after year, but they were ignored until finally something resulted in her leaving. This was an outlier, but only marginally. I could probably tell at least a dozen similar stories.
The higher ed system went from an experience designed to "teach you how to think" to a trade school with a few liberal arts classes slapped on top of it. But don't take my word for it.
I've been saying for years now that once many industries come up with a better credentialing mechanism for technical aptitude (aptitude including the ability to pick up new skills, not just rote memorization of existing techniques), then American colleges are in serious trouble. Colleges are saddling kids with jaw-dropping levels of debt under the guise of an elevated educational experience, yet students aren't even really learning how to critically think in college.
I'm not saying this new program by Google is "the answer", but I'm glad to see companies who are thinking about the problem in different ways. It makes sense: you have to pay a student coming out of college with $150k+ debt far more than someone without nearly as much debt, so it's in their best interest to find ways to improve the educational system.