No.
Why should they be?
If you can't tell whether a person is a drug user during a job interview, most likely, whether they are or are not users, they would still be able to perform on the job.
As an employer, I am more interested in whether or not an applicant uses ANY pharmaceutical drugs, which ones, and how long.
Anything I don't want on my crew is someone who takes drugs to appear normal.
To work for my company, they need to be able to act normal without using drugs to do so.
https://www.youtube.com/watch?v=l5l0PD80u9k