@Bearback I guess your kids are more advanced and adventurous than most!
The junction has a tight fit and a big overlap between the two tubes and has nylock bolts holding them together. Same idea as a shock mount/ linkage on a full suss bike which only have two bolts holding them together.
@AdamT indeed, for off road bigger wheels can be better (but lets not get into 26,27.5,29er debate!) and as a balance bike the 14″ wheels are bigger than typical starter balance bikes (earlyrider. islabikes, strider etc) which use 10 or 12″ wheels. Yes for older kids the wheels are smaller than some bikes but then it’ll be nice and agile.