Liz.
We fly stacked Flexifoils power kites, Bullets and Rage and and Naish Torch and a selection of one off stunt kites.
A child flying a simple kite is one thing on a sites play field.
Any half decent pro looking kite can be very fast, a 6' Fexifoil when stacked can do 100mph plus.
I have kite flying friends in Holland who have seen some really bad accidents with kite lines and even a light weight kite at speed can bowl you over.
10 years ago we flew kites on a beach in France with other caravannners and an English chap and his son joined the queue to have a go, the next day he went out and bought two 10 foot Flexifoils, with no experience he got dragged across the beach over rocks after he'd reluctantly taken our advice just to start off steady with one.
It was an ambulance job and I think the end of the families holiday, in a crowded camp site play area it could have been a disaster for someone else.
If a kite goes down people often grap the lines rather than the kite if the wind catches it, the Spectra / Dyneema lines will cut you to ribbons and do not break.