I'm also a 4 and have had children's, boots, sandals and trainers over the years. Cheaper and the Clarks trainers were shades of blue, not sodding pink.
Jones the boot makers, do some kids boots right up to size 6, much to my 16y DDs delight. Yes they are cheeper, but also they have soft flexible soles. She and her mates are big kids, they race about, climb trees and suddenly decide to go shopping in the next town. The only sensible length route to the station is across the fields, high heels do not work.