Whether we choose to think about it or not, humans in their daily lives directly cause immense suffering to the little creatures. Leaving them half crushed, spraying poison, drowning. Have you ever observed these events closely, and possibly worsening the situation for the insect: tear off a leg, peel a wing?
It’s unfair for the same reason if you push a button that seemingly does nothing, but kills another person, it’s unfair to the other person regardless if you notice or not. A life has still ended to no fault of its own.
the difference is that a human life matters and an insect life doesn’t. And the insect situation is real, and the human-button situation is hypothethical.
Matters according to what/whom?