Pretty much this. You probably consume some minuscule amount of salmonella everyday, but its such an insignificant quantity, like a couple dozen individual bacteria that your body has no problem fighting it off. The problem is when those bacteria are given a chance to grow and form a colony before you ingest them. Then your body has a harder time fighting them off and you experience the gut rumbly liquid shit symptoms for about 24 hours. Salmonella is pretty much a nothing burger unless you're an infant or an elderly person already walking up to death's front door. 1 in 30k is the number of eggs where the actual inside of the egg is infected while it's forming inside the chicken, and the temperature is right for the bacteria to form a colony inside that egg. Remember what I said about "insignificant quantity." Even if you use an infected egg to make a salad dressing, or mayonnaise, etc. you are diluting the amount of bacteria per serving, and also likely adding other ingredients that make it harder for those bacteria to reproduce such as acidic, and salty ingredients.