How about vibration sensor? Unless you push the button gently, the sensor should be able to pick small vibration.
I believe that would be interesting if you are near a road or railroad where trucks or trains may shake things around. Not the case, as the intended generator is a warehouse.
I would suggest using vibration sensor which is is very sensitive (e.g. could get reading when you walk or move your chair which use wheel), but i doubt it's cheap or practical.
2) Why is your way more random than ours?
This question should be "Why is your way have more entropy than ours?".