if you indeed have passed the initial test and no further testing at a lab is required, why do you have to sign and watch them seal the sample like its going to be sent out, is that just a chain of command thing?
Its a Chain Of Custody procedure - for your protection as well as the collection site. With an unsealed bottle, spillages and contamination would compromise the integrity of the drug test. Without your signature, there would be no way to conclusively prove that youve submitted that sample. Sample mixups would run rampant without the donors sig (and/or initialization) .