There are a lot of things than can go wrong when you order from a restaurant or coffee shop. There could be diseases, bacteria, virus, chemicals or even contaminent such as glass parts or insects. The answer to this question would be to only order from places you trust - and even then, contamination can happen quickly and in invisible ways.
I've worked in several, and if you mean "infallible" OK, but I can assure you the people I worked with gave a damn, cared, and would never intentionally slack off, or do a poor job, placing people at risk.
