Answer

I don’t think this is a moral issue. It’s a social convention, perhaps based on the fact that they have life experience, and it is worth treating them with respect because then people will listen to them more and won’t look down on them. Sometimes we are required to honor them in practice because things are harder for them (for example, standing up for them on the bus). Still, now that there is such an expectation, even if it is not entirely justified, perhaps deviating from it is not appropriate.