"Take the current trend for ballet pumps among girls. They offer no support and are very flat. If you have an active child running around in them it could lead to Achilles [tendon] problems in the future."
Surface running on. How you run. What you do. The human foot has evolved for a variety of things - generally speaking walking short and long distances over medium-soft to soft terrain. It wasn't designed to run 26.2 miles on pavement or concrete. Let the foot walk naturally. Run naturally. Take off your shoes and run around on some green stuff or on dirt or sand for a bit, but ease into it.
Your kids shoes is a huge expense sometimes. Colder climates and whatnot. Shop second-hand and try to find stuff that lets their feet walk naturally. But then again if it's stuff they don't want to wear then ...they won't wear it much. Talk. Educate. Understand.
Not everyone can walk around in flip-flops and sandals year-round. Yay San Diego. But don't cram your toes into nasty tiny little things that make me wince every time I see a cute woman in them.
It is worth going to a shoe shop because proper shoe fitters will have undergone specialist training, either through their employer or with the Society of Shoe Fitters.
Training developed by whom? Doing research paid for by whom? Pay to play. Pay to recommend. Industry so-called "experts" funded by the industry. Nike. Adidas. Form follows design follows money follows marketing follows advertising.
Set your feet free. **** the big shoe corporations.