It's not legal to make job decisions based on age. What you're describing is all too common: Without intending to discriminate, some employers rely on stereotypes and assumptions about particular groups of people when they make decisions. Whether the stereotype is that older people can't turn on their iPhones or that women can't use power tools, this type of thinking is biased. Making decisions based on stereotypes about protected groups -- rather than by assessing the actual skills and abilities of individual employees -- is illegal discrimination. For more information, see Nolo's article Your Rights Against Age Discrimination.