Fit 4 Work?
If you look at a lot of job postings today, what is becoming very common under 'selection criteria' is 'must be able to pass a drug test' or wording to that effect. Now, there is no real limit on what an employer can demand for a pre-employment drug test as, to my understanding, provided the test is not discriminatory (i.e. only testing applicants under 25) then the test is legally permitted for probity.
However, Apart from the Australian Defence Force, Police and Corrections Agencies I am not aware of any employers who expect anything other than Australian Standards testing.
If you are applying to the ADF, Police or Corrections, they will not accept a drug test you walk in with, just like they won't accept a third party background check. Do not pay a third party for a test as those agencies will conduct their own testing and will refuse your supplied test.
When should I get a pre-employment drug test?
If you are shortlisted for a job, an employer may ask you to provide the results of a drug and alcohol test. The easiest interpretation is you can pick whomever you please if you are required to pay. If your employer has an account with any entity and are paying the bill (Sonic Health Plus are the McDonalds of pre-employment testing), then you would need to go to their chosen provider provided it is a reasonable distance from the location of the work and/or residence.
You should only be paying for a pre-employment drug test if the employer is not willing to. Once you are working, you should not be paying any costs for ongoing drug/alcohol testing. If an employer is making an employee pay for a test, report them to the Fair Work Ombudsman.
Who receives the results?
Regardless of the reason for the test, the donor (person being tested) will always receive a copy of the results, but not a drug test report. Whoever is paying me can name a 'requesting authority' and I will deliver a formal drug testing report to the 'requesting authority'. If you want one on file for potential employers, you can name yourself as the requesting authority or you can name 'ABC Builders Pty Ltd' and they would receive a copy of the field test and a formal report.