It's not a question of miles, it's a question of scenarios. A car that takes on the entire interstate highways system but suffers no "close-calls" is practically untested, IMO.
Also, that car never "experienced" rush hour in crazy places like downtown Cairo or the old&narrow streets of older Italy.
As a part-time CS teacher and part-time developer, I can sadly say that quite a few people in the industry are in the wrong line of work.
However, I wouldn't say that interviews are a valid measure of skill. They're short and often done incorrectly.
Before you give up, you might want to seek elsewhere for validation. You might just be choosing the wrong places to interview with.