1. Flat hierarchies. In SE, there are officially only very few levels between a grunt and the CEO. In the military, hierarchies are deep. You have squad leaders, platoon leaders, sometimes even more staff, company staff, and so on. That means the gradient between a leader and someone being lead is rather small. Ideally, everyone can step up to a higher position immediately (useful because of the, ahem, high fluctuation).
2. Planned career advancement. The military has always agreed that leaders (that is, officers) require special training. But that training comes after they have learned the fundamentals. In SE, most managers come from dedicated management backgrounds. If an engineer becomes manager that is considered unusual and difficult.
3. Strategic training. Officers have wargames and even colleges dedicated to improve their decision making. SE Managers have what? A few books on amazon? It's not just the how that is important in great leadership, the what should not be forgotten.