Scope != headcount, in matrix orgs (like big tech) there are directors with very small orgs (5-10 people)
For that promotion to director, you usually need at least 50 reports and at least 2 levels of management. And then the span of responsibility for (senior) director goes on up to about 500 reports. It's not unusual to have directors with less than that - but usually that is because they once had a big org, their scope and responsibility decreased in some re-org, but upper management is keeping them around so they have a deep leadership bench. Another re-org and they can easily end up with 500+ people again.