Can my kid use a lawn mower or power tools?

This is where kids actually get hurt, and it gets far less attention than door knocking does.

There is no single age that answers it, so use a standard instead: a kid should be able to tell you what would go wrong before they do it. A kid who cannot name the failure mode is not ready to work unsupervised, no matter how many times they have watched somebody else.

Three questions underneath that. Can they physically control it, including when it catches or kicks back? Do they understand what happens when it goes wrong? Have they done it under supervision enough times that nothing about it is still novel?

A few specifics worth knowing.

Mowers get treated casually and should not be. The blade, the debris it throws, and slopes are all real. Push mowers are a different proposition from riding mowers, and riding mowers deserve considerably more caution than they usually get.

Pressure washers are the most underestimated item on the idea list. The pressure that strips paint from a driveway does serious damage to skin, and injuries from them are worse than they look at first.

Anything with heat or a blade needs real supervision before solo use, which covers a lot of the making and food ideas.

Ladders and heights are the clearest line and the easiest to hold. Gutters and upstairs windows are worth a plain no, and the no should survive a good argument, because a fall is not something a business recovers from.

Bear in mind that your homeowners policy may exclude business activities, which is worth a call to your agent before power equipment is in regular use rather than after.

And the useful default when a kid wants to take on something beyond their gear or their competence: that job is a no, and here is what you can do instead. A specific alternative lands much better than a flat refusal.