It is essential in order to protect the public. Otherwise, parliamentarians and society are going to have to live with the consequences. If you want to have a law that is objectively the same for all, go for zero tolerance. Then the system will no longer be able to make a mistake in one case and be right in another. As it stands, there are no provisions for police forces to look after breathalyzers. As a result, police forces have no duty towards the people whom they stop and ask to blow into the device. That is for sure. We see it every day in our job.
Recently, we had a case that took 33 days of proceedings to finally discover that the police had done no maintenance and had not checked the device when it was repaired, not the first time, nor three or four times a year afterwards. Yet the device was getting older and less accurate with time. No values were checked other than the 100 mg. Now, under the Criminal Code, if a person blows more than twice the legal limit, the judge must impose a harsher penalty. If we choose to be repressive—that one was a choice that society made—objective measurements must also apply.
In this case, you are taking away any possibility for people to defend themselves, but, given that some physiological factors prevent a blood sample being taken, you are not requiring police forces to be sure that the result they get is realistic.