There are of course times where a person cannot be accommodated in a certain role, either temporarily or permanently, and the law understands this.
There are certain job requirements so intrinsic to a role, that if an employee cannot perform those exact duties then they are unable to continue in a role. A furniture mover may be legally required to lift 50 lbs or more, which would disqualify anyone who cannot meet this condition from working in the role. Similarly, a requirement for an employee to have a driver’s license as a necessary part of their duties may rule out an employee who is unable to drive due to age or disability, even though both are protected human rights grounds.
These requirements are known in law as bona fide occupational requirements. The name implies that they are requirements made in good faith, and not for the purposes of excluding a specific individual or group. Even though an employee may seek to challenge the restrictions in court, employers have a strong defense when they can prove that a decision was made based on a bona fide occupational qualification or requirement.