Last year a company was testing their software in a dev/test environment and accidentally sent out an "Integration email" to their customers. They blamed this on an intern, though a little jokingly, and plenty of people shared their own stories about making mistakes.
I did this once, and only once. I was doing some software testing on a copy of the production database and accidentally sent out thousands of emails to customers. I hadn't scrubbed the email addresses in the copy, but since I also hadn't scrubbed the data, customers got an "extra" email for their account and few complained. My boss, however, complained quite a bit and with good reason.
These days using production data in dev/test environments isn't really an acceptable practice. Plenty of organizations do it, and hopefully, they are taking precautions. Kendra Little wrote a little about what happened and what should be done, including scrubbing out sensitive data. Not enough people do this, though I am seeing more and more companies looking for solutions that prevent data release.
This isn't an intern's issue. I appreciate someone making a bit of a joke here, and hopefully, there were engineers that taught the intern something. The bigger issue is that we make mistakes as humans and our protocols and processes should expect that. This is one reason why adopting automation in our software process is important. Whether that's deploying code to the right production server or refreshing the non-production databases, we want to be sure that we limit the number of human mistakes.
There are always places where we will use humans to perform a process. Whether that's typing code or clicking something. It's entirely possible someone clicks the wrong button or types the wrong item. As much as possible, we can use automation to provide a safety net to prevent these issues from reaching customers. We can't prevent every mistake, but we can continue to improve our process but adjusting it over time. At the very least, we ought to prevent the same mistake from happening over and over.