Under what circumstances would a company require access your medical records?

by Driver
(USA)

As a part of the pre employment process, a medical examination, including drug testing, will be required after a conditional offer of employment. I further agree to provide access to previous medical records if required.

IF required? So what circumstances would they require the medical records of an employee. In the even of an accident? When signing up with the company sponsored health insurance? If you have no prior health conditions why would the company need to look into you medical history at all?

Am I right to assume if the driver passed the dot physical without any need for medications to regulate any condition there would be no need for the company to access the drivers medical records?

What do they mean by IF required?? What would necessitate such a review of my medical records?