It's more like humans can't tell how old any particular Adolebi is and the Adolebi take measures to make sure nothing gives away their age. Humans have a rough idea of Adolebi lifespan, but it can be hard to tell. Adolebi usually don't stay in one job for extended periods of time either, so they're usually not in contact with any one individual too long, or sometimes even the same organization, and Adolebi generally stay on their homeworld for a while before leaving, so their age is pretty foggy to other people. Not to mention Adolebi are very secretive about their actual biology, though there are rumors of people like the Bleeding Heart Society killing Adolebi and studying them, and corporations secretly kidnapping Adolebi and cutting into their suits. But that's just rumors.