This article is from the PE and EIT Exams FAQ, by Ron Graham ecaxron@ariel.lerc.nasa.gov with numerous contributions by others.
"Because of the industrial exemption" is the technical answer, but
there are other underlying trains of thought.
o Some industries are already regulated on a federal level,
such as aerospace. [Utay]
o Some individuals who do not work with PEs have no way of
getting the five references required to sit for the PP Exam.
[Lindelef] In some such cases, an application may be
considered individually anyway. [Moskalik]
o The application procedure can take longer than the exam
itself. [Moskalik]
There is a move afoot nationally to eliminate the industrial exemption.
[Lumos]
 
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