Don't wait for others to do so; keep that power to yourself. You don't need their politeness to feel good about yourself. And do not distract yourself by fretting over something that is not under your control.
They might want that flexibility so that they do not reject you too early, by leaving their options open. Besides, the sheer volume makes it impractical to reply to each rejected candidate.
(Why do you feel the need to 敬仰 a business entity? By doing so, are you off-loading something from your own shoulders? It's a business transaction, keep it as what it is. Don't weaken your position by being sentimental.)