Having worked a decade and a half in Japan, I can vouch that it is true.
Drug abuse is not unknown in Japan but neither is it considered so normal that it would qualify you to hold the highest elective office in the country.
The point is, that before there were drug tests, there were employees that used drugs and no one ever knew about it. It seems that if drug testing was dropped, then, as you said, there would be more employees available. It shouldn’t be a reason for not hiring someone. The lower-level managers and supervisors would actually have to judge people on their performance and attendance.
Take marijuana off your testing list, and my guess is that you’d have a LOT more applicants - qualified, hard-working applicants as well. Like someone else mentioned the prescribed meds that are “legal”, and even alcohol are more likely to be a big problem than someone who smokes a joint upon occasion.
The problem you have is that marijuana stays in your system for a long time in comparison to all of the other drugs you are testing for even though it is probably the most benign of them all - you could have someone who smokes perhaps once a week, on the weekends - or with friends at a party on occasion, and is completely sober at all other times, but will not be able to pass your drug test - particularly if your company is the type to do random screenings. For instance, you could have an employee off for a 3-day weekend that snorts cocaine the whole time, and say you pop a drug test on them on that Wednesday, and depending on age, weight, metabolism, etc... they could PASS the test.
Other drugs are out of one’s system in a matter of HOURS, and are WAY more likely to interfere with one’s performance on the job. Also, take into account that you could even have someone working for you that USED to smoke, and weighed a decent amount - if they lose the weight very quickly and you test them they could come back with a positive result (depending on how much they used to smoke, and how much weight they have lost quickly as it gets stored in your fat cells - not enough to make you “high” again, but enough to register on some tests once in a while). Granted, these are rare circumstances, but they do happen. Most people won’t, like you’ve noticed, even risk going for a job that tests for drugs - even if they are merely around friends who perhaps smoke marijuana because you CAN show positive from second-hand exposure. And, yet there are even many others that will not work for a company that tests - not because they do drugs themselves, but because they see it as a violation of their personal rights to do as they wish when they are not on the clock.
It’s honestly ridiculous, IMO, when a full-fledged alcoholic would be able to get hired, and depending on the amount they drink and how often they could still pass your test, but someone who smokes pot here and there would not - even if they NEVER, EVER get high when they are working. It’s not like you can’t tell when someone is high AT work - and that’s a completely different story, IMO. Most people also realize that if you are the type who partakes and you get hurt, you will likely not see a dime of any insurance money, etc...
That’s my personal opinion, and I know many others differ on the assessment of policies, and even risk with hiring. AND, the only reason I know some of these things is because of research when I was working on political stuff as far as the Constitutionality of drug testing. :)