We cannot always treat everyone the same and ignore the differences that an individual or group of individuals have. Like humanity, no one is perfect and unfortunately, there are many people out there are worse off than others in terms of living. Additionally, not everyone is necessarily “accessible;” there are certain cultural barriers that can make it hard for people to communicate/perform a told task without ease or experience.
For example, if a first generation immigrant comes to the US barely speaking English and finds work to support him/herself, a manager cannot expect that person to perform on par with let’s say a person their age but of more grasp on the language/work culture. Similarly, if a foreigner immigrates 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.