If rivets were used it would be difficult to replace a broken side piece. It would also be hard to tightenup the arm when it got loose. You can take them to almost any outlet that sells glasses. They will likely replace the screw at no charge. It just makes good business sense to help out.I do. Just now one of the lenses fell out because a miniature screw fell out.
Of course there was no chance of finding it
Now I have to go back to where I purchased them for repairs.
Such a design flaw that has been around for as long as the modern era glasses have been around.
I think a better method would be to use rivets instead of screws.
They would never fall out.
If one needed stronger lenses, then the rivet could be drilled out.