One thing people in Florida do not always realize is that driving is considered a right, not a privilege. This does not mean that the DMV in Florida is going to withdraw drivers' licenses for no reason, but it does mean that when the DMV does revoke a person's driving privileges, that person may have much less recourse than in criminal cases where Constitutional rights are at issue.
For example, in DUI cases, the DMV will almost always suspend a person's driver's license based merely upon a DUI arrest. Of course, according to Constitutional law, a person is innocent until proven guilty and an arrest, by itself, is not proof of guilt. However, since driving is a privilege and the DMV operates under its own set of rules, they can suspend a driver's license immediately upon a DUI arrest. The driver will have an opportunity to challenge the license suspension, but that process does not have anywhere near the safeguards and thoroughness that comes with a criminal case.
The DMV can also suspend your driver's license if there is an indication that you are not medically fit to drive. All it takes to start this process is a report from someone that you are not medically fit to drive. This can be a doctor or anyone with any knowledge of your ability to drive. If someone makes such a report to the DMV, the DMV might open a file and send you a letter telling you to go see a doctor and get examined to see if the doctor thinks you should be driving. The doctor would then prepare a report that goes to the DMV. If the doctor concludes that you are not fit to drive, the DMV will likely suspend your license until you can prove, with the assistance of a doctor, that you are competent to drive.
Additionally, if the DMV sends you a letter indicating that they have reason to believe you are not fit to drive and requesting a report from a doctor and you do not comply, the DMV can suspend your driver's license until you do comply with the DMV's instructions and get an evaluation and report from a qualified doctor. In the meantime, you are not allowed to discover who made the report to the DMV or what the person said to the DMV about your medical condition and your driving. There are probably a few reasons for the confidentiality of this process, but I assume one of them is to encourage people to report family members without that family member knowing.