I think you're making a lot of assumptions about the nature of the team and the level of communication the team considers normal. I'm literally talking about teams where no one ever tells anyone else what they're working on outside of standup, which happens a LOT. The fact you've never encountered this tells me you probably haven't worked on that many different teams. Over time, yes, even an individual contributor can mold a team that doesn't talk into one that does, but it's an easier sell to get them to start telling each other what they're doing in standup than just randomly saying it because someone else might want to know.