Exactly! For any medical tests, there are 2 measurements: sensitivity and specificity, one to judge false positive and another judge the false negatives.
https://www.nytimes.com/interactive/2020/03/27/world/europe/...
Because you hypothesize that they can rapidly learn new, not very distinctive patterns without much data?
Of course not! We've got half a million cases now, hundreds of thousands cases in hospitals, and hundreds of papers published in all the medical journals. So yeah, data is rich.
Regarding CT scans .. machine learning will be so much better than humans in classifying those once enough data is available... it‘s completely out of question for me as an ML researcher.