Why don't grocery stores/manufacturers pre-wash berries so we don't have to?!

You are supposed to keep your berries unwashed and in the refrigerator. Rinse them right before eating. If stores rinsed them for you there would be grocery stores filled with moldy berries that no one would buy.

Because even if they did pre-wash them there is all those people touching them. From packaging to grubby fingers (and mouths) in the stores. Even if they said they washed them I would still wash the. And really, for pesticides, rinsing is all you really need to do. Hold them under running water should be good enough to wash off the chemicals.

Berries are very sensitive to moisture and molding. Even when you wash berries at home, you need to eat them within a day, two days at the most, or they will start growing molds.

If you don't the pesticides are long gone but the need to keep them dry or they will mode

because of people handling them.