No needle involved in that case (if it's the one I am thinking of). That was a case where a cath came disconnected. Clinic policy was to discard the blood setup and not reconnect. The tech didn't do this, presumably because this would require a blood loss incident report. This sort of thing is much riskier with a cath because the infection goes right to the heart. There was another case where a tech was convicted of intentionally injecting bleach into the circuit to kill patients.
But, you are right - if a needle "pops out", or has to be pulled out because of a missed stick, infilitration, etc. policy is to use another needle. There is less risk a tech will skip this step because using an extra needle on a patient is not a "reportable incident" (which no tech or RN wants to be associated with). Similarly, if there is an error and the needle accidently touches a non-sterile surface (for example, brushing it against the arm), it must be discarded and replaced with a sterile one.
Good advise about making sure the tech or nurse changes gloves between patients. There was a case of a Fresinius patient who popped a needle which freaked a new tech so the needle was reinserted the patient then died of a blood borne staff infection. If a needles pops it must be replaced with a new one.