I mean all people. When you work on the laptop you probably connect more things than a network => you have a dock => you don't need the rj45. So there might be negligible amount of corporate workers that need it, and some portion of tech workers, maybe. But overall, out of all customers, it's not enough for the hassle. Especially since it has drawbacks for the rest of the customers.
it's perfectly feasible to integrate one.
just look a the dell latitude 7390. really, look at it:
https://cdn.mos.cms.futurecdn.net/eB6gGRDZWSYT4XW6SeSMtf-120...