This is exactly the scenario in the book "Momma Don't You Worry". The difference is, the kid involved here is already six years old. The book has a fun rhyming tone and has illustrations that fit the story well. This is a good read for children so that they will get the lesson that they shouldn't go alone especially in public areas.
Kids will also realize that they may think they can already do something despite their young age but actually still need their parents. It can also give them a lesson to always listen their parents too. I always tell this to Bella. Listening to Mom and Dad will do you no harm. It is always for their own good.
This can be read independently by kids or can be read to them by their parents. The story will also be able to encourage interaction between the parents and children. When it is time to go out in public, the story will be a good reminder to them.
The book is written by Louie Lawent from LadyBee Publishing. You can get the book from Amazon as well. This could be a nice addition to your kid's ebook collection!