Typically most real world gears vary in teeth shape. I mean among the gear pairs. Some are more pointy and some more round. What we see here is probably optimum teeth form.

I have done some calculations about them. But the manual I used was so vague about everything that I can't honestly say why and how for certain. My current understanding is that first you select gear ratio, then you get somewhat good nominal distance for the axels, and then you adjust teeth shape to accommodate all that.