1. If you think the person assembling this, assuming a person was even involved, is looking at those parts then you’ve never worked in/near a low wage factory assembly position. The time to inspect things isn’t there, and neither is the motivation. I once worked at a place where we assembled parts the size of a shoebox. One of our samples, spray painted bright orange, ended up in the workflow. It finally got noticed 4 or 5 operations later not because it was bright orange but because the paint prevented it from fitting together.
2. You get what you pay for. Maybe the karma hit belongs to the person buying cheap junk for a child and then not making sure it works first. Think you can provide better quality at that price point? There’s a market if you can.
Good on you for making it better, but I would go easy on laying lame on someone who probably doesn’t realize they committed the offense that bothers you.