This style of programming interview is directly descendant from early microsoft. Some of the best minds in the business of making software engineering organizations cut their teeth on the topic (maybe microsoft isn't so stellar now, but how many organizations from that period are still making software that works at that scale?). Bill Gates pointed to the MS hiring strategy in particular as something that set them apart from their competitors.
However, there are lots of other fields that demand a certain level of competence for you to pursue them. Interviews at investment banks last all day, and they ask for pretty serious mathematics exams among other things. Lawyers must pass the BAR, which is fairly brutal. Actuaries must pass the actuarial exam. Musicians and dancers must audition. Aspiring professors must give a series of 'job talks', opening up their research and program to the criticisms of an entire faculty, after which they continue to meet one on one for hours at a time.
By contrast, the hours spent in Google interviews seem comparatively simple.