There are differences between medical cannabis and recreational marijuana when it comes to driving. While the MMMA states specifically it supersedes conflicting state law, that is not part of the recreational marijuana law.
People v Koon general description: https://michigan-marijuana-lawyer.com/people-koon-michigan-supreme-court/ “The MMMA does not define what it means to be “under the influence,” but the phrase clearly contemplates something more than having any amount of marijuana in one’s system and requires some effect on the person. Thus, the MMMA’s protections extend to a registered patient who internally possesses marijuana while operating a vehicle unless the patient is under the influence of marijuana.”
“The Michigan Supreme Court (People v Feezel, 2010) ruled that the marihuana metabolite “11-carboxy-THC” (the substance that stays in your body for up to three weeks) was a ‘derivative’ of marijuana As a derivative, 11-carboxy-THC is not a Schedule 1 controlled substance. Thus, a person who only has the metabolite cannot be prosecuted for zero tolerance drugged driving. Although it is illegal to drive with active THC, it is not illegal to drive with the 11-carboxy-THC metabolite in Michigan. But be aware, we have heard that driving with the marijuana metabolite is still illegal in many states.”
These court cases specifically addressed MEDICAL CANNABIS, it is unknown how the courts may handle recreational marijuana- it is interesting to note that the Koon Case cited above did address the differences between the MMMA and the standard driving under the influence laws. We may see more of this in the future.
The bottom line is that there are clearly more protections for medical cannabis users when it comes to driving than are available to most citizens and recreational marijuana users.