4 might be a little young, but if they're out by themselves. being able to call for help is priceless.
Discussion
Most people now a days don't even trust their 8-12 yr olds out riding bikes by themselves... 🙃
we had a 14 y/o in our town that was almost abducted. she took a pic of the van & license plate. they picked him up in 20 minutes.
I get people are worried about kids screen time, but i think that's a parenting/discipline thing.