Agreed. Stills and motion pictures present two different scenarios for the lab operator to work under.
The OP did ask, specifically, about Super-8 movie film but the question of still photos is also valid.
Seeing as there are far fewer rolls of film being developed in consumer oriented labs, I would suppose that the number of images that any one operator has to look at has gone down. As such, the amount of attention he has to devote to each one is likely to be greater. Thus the chances of a "bad" image being caught are higher.
I still think "image overload" applies. Just not as much as it used to.
Do you think that the average lab operator even gives a rat's a$$ about other peoples' pictures past the point where they are properly developed, printed and packaged?
Then we have to consider that "community standards" of what constitutes a "bad" picture have changed over the years.
50 years ago, or even 20 years ago, people had a lot different view of what pornography was. A bare bum would have been scandalous but a picture of a nude child might have been considered innocent. Nowadays, the paradigm is almost totally reversed. We see full frontal nudity and sex on television, these days. We can go on the internet and see any kind of pornography we want. Movies like "Deep Throat" are now laughable. On the other hand, a little girl playing on the beach, even if wearing a bathing suit, will cause people to look sideways at you.
I'll go back to what I said before. Even though most lab workers don't give a damn, if you send them a nude shot your picture might end up as a pinup in some back room, somewhere but, unless it is really out of the ordinary, I don't think it will even be noticed.
I think the real consensus, when an operator is doing their first 50 rolls, the occasional nudie, is a big deal, after they have been doing it for 20 years, and the number of rolls they have processed is 50,000 then they probably all look the same. Even fully automated systems will kick the problem images out for hand printing, and you can bet an operator is going to notice something in the say 10 images kicked out per day. I think the real question though, if your pictures contain illegal activity (like kiddie porn), then do you really want to risk that the lab guy is going to notice and turn your pictures and contact information over to the local constabulary.