Hollows have far lesser SE because they lack such boosting weapons as Zanpaktou. However, they make up for it in Numbers, Special Attacks, and pure viciousnous.
Now, if you look at the Arrancar, you'll find they have FAR more SE then Shinigamis. This is because Arrancar are fewer then Shinigami, and is to make up for their Weaker Hollow Selves.
But, as I said in my plans, I WILL be accepting two other Espadas.