I'm also confused. It's my understanding that staff engineers are responsible for taking the software into a certain technical direction. "Upper management" related to engineering. Wouldn't that automatically involve managing those engineers who are involved with the project(s)?

(broad generalizations ahead) Technical management and people management are different jobs. People management involves a lot more focus on hiring, performance evaluation, and performance management. It also tends to have many more meetings, including 1:1 meetings with all of your reports weekly or biweekly. This generally does not leave time for significant individual contributor work.

Yes, I've had meetings with those people managers. I would consider them more HR type managers. After some reading it's my understanding that - from an HR perspective - the main difference between a manager and an "individual contributor" is that the IC doesn't have direct reports. Since those tasks would take up too much of their time. Those tasks are being transfered to the HR style managers. But the IC still performs many tasks which are traditionally considered "management responsibilities" with their day-to-day work.

It’s frequently a high level IC role that is more technical leadership than people management.

I have a fairly high level IC / lead engineer role with two other team members (1 junior and 1 medior). I need to keep an eye on their work. Provide direction on how things can be implemented. I'm not their official manager. We have chapter managers for that. But chapter managers are more HR type roles. They aren't managing the day to day work. I guess my role is more close to someone managing the daily work of the team?

Isn't this a responsibility of a an engineering manager and core competence? I believe Staff engineers work across squads and tribes to help solve various technical and architectural challenges.