Not to mention that some insects even have a bit of contrast between the lenses so it's easier to understand they are compounded.
And additionally due to individual lenses compounded eyes arent smooth - by reflecting light at different angles you can make the "bumps" obvious.
Also if there is like a water droplet on grasshoppers eyes you can clearly see it's surface structure. Just like you can see individual pixels on your (high dpi phone?) screen the same way.
An alternative that I like to use in the lab is squinting and holding the sample really close to my face. Perhaps they used my method if the bugs weren't big enough?
For sure, I just like posting stupid things on memes.
I think your lab needs to get you a giant magnifying glass with a light so your squinting days can continue. They're super nice for things that can't go under a microscope. So far I've been lucky myself, but many of my colleagues my age experience the same problem. Some day I would like to get a macro camera so I can just show them pictures.