This is gross negligence by the boss, and it's very very common in smaller construction companies and crews. Allowing a minor to operate heavy machinery is ~~dumb~~ illegal to start with, but the kid learned unsafe behavior from his coworkers, who likely never had any proper safety training themselves. Garbage in, garbage out. (Walk behind trenchers are shite anyway, pay the extra $50 to rent a ride-on trencher)

There is a place for teenagers on a construction site, but it's not in high risk areas or work. So much can be learned about work ethic, practical skills, and the challenging realities of construction without risking life and limb.

I grew up in a construction household. My dad was a small time contractor. Custom homes, spec builds, one at a time, bank financed, that sort of thing. I go into that detail to say we weren't rich, not even middle-class until I was almost graduated from high school (secondary school). Also this isn't an endorsement for how I was raised, just my lived experience.

I learned to run a skid-steer at 13. I was cutting lumber for the framers by the time I was 15. In many ways the skills I learned as a child set me up for success as an adult. But I also learned so many unsafe practices and endangered myself from a young age because of that casual familiarly with dangerous work and locations. The entirety of my twenties was spent unlearning bad habits and practices. I'm still working at it now.

The only time teenagers should be working on construction sites is if the company has a very strong safety culture, which means they won't put kids in high risk situations. Parents should absolutely be checking these things before allowing their kids to work

Now, I gotta ask.... Why are you implying that it's better for a person 2 years older to handle the same machine with the same lack of safety features/proper supervision? Everyone here is making a big stink about this being a "kid", but a few years older and this is the reality for many many people. Also the same age we let them start driving.... So why are you only seemingly outraged that it was a kid? Shouldn't you be outraged that it could happen to anyone, and in fact regularly does, and is usually not given any attention?