We cannot always treat everyone the same and ignore the differences that an individual or group of individuals have. Like humanity itself, no one single person is perfect and unfortunately, there are many people out there who are worse off than others in terms of living (setting or quality of navigating through it). Additionally, not everyone is necessarily “accessible;” there are certain cultural barriers that can make it hard for people to communicate or perform a told task without being put at ease or having experience.
For example, if a first generation immigrant comes to the US barely speaking English and finds work to support him or herself, a manager cannot expect that person to perform on par with let’s say a person of their age but with more grasp on the language and work culture. Similarly, if a foreigner immigrates to and studies in the US with little experience in the language and even learning style, a school cannot expect their level of processing information to be comparable with their more experienced American peers.