I agree with parts of it, but I disagree with the basic premise that hiring programmers is like renting cars. When you hire a programmer, it is like hiring a car mechanic, not a car driver. Some of the questions do seem appropriate to ask to a car mechanic.
Car Mechanics dont build the car parts or research into how to build the most efficient engine, but do need to know how to apply the knowledge of those parts. The best car mechanics can apply the science but may not be the best car researchers. Thats why in my opinion, some questions do make sense for a car mechanic.
If you were using the photoshop analogy, then I think to interview someone, you need to ask them how different features of Photoshop work, not how Photoshop was built but also not how they draw in general, IMO. You may be a great artist, but if you can't understand Photoshop features and what they mean you will fail to create a great digital painting.
The car mechanic analogy is an interesting one that I came across while touring universities to find one that I liked. A parent at one of the Q&A sessions asked what the difference was between Computing and IT (in a UK education context). The degree director replied that an IT course is like learning to drive a car, whereas Computing is like learning to be a mechanic.
(Context: IT classes pre-university used to consist of learning to use Word, Excel and Powerpoint.)
So I suppose whether the analogy works depends whether you want your programmer to find and plug a hole in your exhaust pipe, or to work out how to make a more efficient catalytic converter.
