I'm a senior leader at Amazon and have seen many bad managers. Here are 3 reasons why there are so few great ones.

• Brandon Southern is a senior leader at Amazon and former head of analytics at eBay and GameStop.

• He writes that very few managers actually have a strong desire to elevate others. 

• Southern also writes that managers often sacrifice employee growth to meet deliverables.  

I've seen a couple of good leaders, and a lot of bad managers throughout my 20-year career in tech and as a head of analytics at companies including eBay, Amazon, and GameStop.

I spent time reflecting on why so many managers fall into the category of a bad manager, instead of into the category of a great leader.

There are three main reasons why this occurs.

1. Most managers didn't set out to be a leader or manager

Almost all started out as individual contributors, and many then found themselves working in management because it was the next logical step on the career ladder or because it provided a higher salary.

Few managers seem to have had a strong desire to become a people leader. While I don't have quantifiable data, I've always felt like 90% of managers found themselves working in management by accident, 5% were power-hungry and wanted control over others, and 5% had a strong desire to truly elevate others.

This isn't to say that the managers who found themselves working as manager by accident or as the next step in their career are bad managers. But if leadership isn't something that they have passion for, we're already on unstable ground before the work even starts.

2. Too many focus on actually managing instead of leading

Every company employs managers and almost every manager working today has a job title with manager in the name.

This is a huge disconnect from what individuals and companies say that they want, which is leaders.

People should be lead and process should be managed. By calling someone a manager instead of a leader, the implied focus is on managing — which usually spills over to managing people instead of leading people. This issue is so pervasive that it goes without notice in all our lives every day.