How is it that very few adults seem to have "friends"?

I know this does not apply to everybody, don’t want to generalize, but most adults I know never have actual friends. Maybe acquaintances or “colleagues” they talk to or use in business manner etc. but never true friends. I always thought of it as a sad, lonely prospect, add one more reason to my list of never growing up. This is especially a case I see when the adult is espoused, and this more applies to older adults(like over the hill or approaching doing so). My older bro, who is late twenties though, seems to be heading down that road. It seems that adult life is significantly more business, less leisure, leaving less time for “real” friend relationships. Why is this the case that adults seem to not have friends? Is there something that makes up for it?