Pardon? Factories have caused all sorts of problems with discharge, intentional or unintentional. Here's some from the top of my head:

https://en.wikipedia.org/wiki/Bhopal_disaster (mismanagement at a pesticide factory causes an explosion, poisoning many people and permanently contaminating the surrounding landscape).

https://en.wikipedia.org/wiki/Minamata_disease (a factory discharged mercury into the sea for years, where it interacted with anaerobic bacteria in the sediment to become incredibly deadly organic mercury and poisoned an entire town)

Keep in mind, these are from the top of my head and I am a nonexpert; we have environmental regulations because people have been hurt or killed by pollution numerous times.

Here's a quote that I hope will emphasize just how powerful pollution can be on an industrial scale:

> Pollution was so heavy at the mouth of the wastewater canal, a figure of 2 kg of mercury per ton of sediment was measured: a level that would be economically viable to mine. Indeed, Chisso did later set up a subsidiary to reclaim and sell the mercury recovered from the sludge.

They literally dumped enough mercury into the river to turn it into a mercury mine. If that doesn't convince you that factories haven't simply been operating with "nothing going wrong", then I don't know what to say.