Most commercially used plant fertilisers are made in factories and are pretty sterile. These man made fertilisers give better results than manures but do not improve the soil structure. So a combination of organic matter to build up the soil and artificial fertilisers are often used in horticulture.If you think you don't find these in vegetable matter, I regret to inform you that you're wrong. What do you think fertiliser is? When farmers spray fields with manure? What do mushrooms grow in?
There are bacteria and micro-organisms all over and inside your body, right now. Whole ecosystems of them. It's a misunderstanding of science turned to fearmongering that seems to be driving your beliefs here.
In Australia, manures can only be used on plant crops several months before the crops get sown, but raw manures are not allowed on growing plants. Same deal with herbicides, they can't be used on crops within a certain time of harvesting those crops. Most countries around the world have similar guidelines.
I'm not saying all farmers comply with these laws but most do and the odds of getting poop on your lettuce is low, but it does happen. Some cases have been linked to illegal farming practices but others have been from people working in packing plants who deliberately contaminate food before it's packed.
But you are correct in there being bacteria everywhere. They are literally everywhere and are on people, food, clothes, soil, plants, in the air, everywhere.