"How can a leader walk right by a group of people they work with and not even say hello to them?"
I've been rereading The 21 Irrefutable Laws of Leadership and came across this statement. At first I ignored this line as I believed it didn't pertain to me. This sounded more like a egocentric, self-absorbed tyrant as opposed to someone who prides themselves on creating an atmosphere where employees feel valued.
However, as I read further I realized there may be more self-truth to this statement than I first believed:
"Don't say 'I've got a lot of work to do today and I really want to get started.' You just walked past your work. Never forget that leadership is about people."
Upon starting my current position I made great effort to speak with all employees in the district office. I was intentional about building relationships and getting to know each individual, working hard to learn what mattered most in their lives.
Admittedly, over time I have become lazy. I have developed a bad habit of prioritizing personal work over relationships with employees in the office. Instead of allocating time strengthening connections, I have been quick to retreat to my office for the purpose of completing "urgent" work.

Those who know me - and the employees in our office - may think this narrative is a bit over-dramatic. Perhaps this decline in interaction is minimal or not even noticed. Regardless of what others think, I realize I am not meeting my high expectations when it comes to relationship-building.
With so many things going on in schools (e.g., COVID-19, Bond Votes, Salary Negotiations, Employee Contracts, etc.) taking refuge in the office to work on "urgent" tasks can seem more important than seeing how an employee's family is doing. However, my personal challenge (and my challenge to others) is to remember that leadership is about people.
Next time you make a mad dash to your office to return that phone call without acknowledging staff remember this:
You just walked past your work.
Looking for a great book about the importance of building relationships? Consider reading How to Win Friends and Influence People by Dale Carnegie. It's currently one of my highest rated books.