I entirely agree with you, but a part of safety culture is to protect yourself and others. To be clear, no child should ever be hired or near these kinds of environments. Child labor, period, is a travesty and doubly so in an industrial or hazardous environment. These environments are barely suitable for adults, especially in the protein industry. If you are working in a place like this where children are hired, don't be a bystander and let it happen. Speak up and hang these assholes out to dry. Complacency and indifference needs to stop, naive a goal as it is.
Based on the teams I have worked with in the past, people in their twenties are definitely just as bad as teenagers. Even people who are far old enough to know better still play stupid games and win stupid prizes.
More safety PSA:
The one thing I at least try and make sure those under and around me understand is they don't have to say yes. It doesn't even occur to them that they can refuse. Workers are told to shut up and take it enough at it is, no matter the job. Workers are told to work 12-16 hour shifts and be glad they have a job at all. We live in a shitty world and if this comment prevents even one person getting hurt, no matter their age, that is enough for me.
Final point is there are plenty of tasks that can be done with appropriate safety measures, but if you are still not comfortable, just don't do it. Nobody can force you to get in a lift or climb that high ladder. Can you potentially lose your job? Maybe, but better than you getting hurt or hurting someone else.