Is it harder to stay attentive in an autonomous car than it is as a normal driver?
1) the person needs to be qualified as a true test driver (experienced auto engineer, professional driver with sufficient experience)
2) physical fitness, especially ability to stay awake and documented measured reaction times
3) strict rules on distractions, random checks
4) engineering measures for staying alert (sounds, tasks etc.)
5) limits on driving times, documented work logs and much more
and plenty more. Someone in Uber should have had the tasks making sure the tests are done as safe as possible. That person would have needed the qualifications and authority to affect the test execution.
The biggest problem is imho. that Uber does not have to produce self driving technology but only needs to be seen as working on the leading edge of it to sustain their financial storyline.