The ESRB and Walmart are OK with kids playing a casino gambling simulator, but that doesn’t mean Google or Apple should be too.
For a parent who looks at their kid playing on their phone with a Vegas-style video slot machine on the screen, complete with a "Spin" button, it appears to be gambling. At a minimum, it’s normalizing real-life casino gambling motifs for their child. Some may find that objectionable for children, and it appears the tech companies agree.
If you can't see that this is 99% of a video slot machine game, just without any cost per spin and 8-bit graphics, then maybe you should visit a casino: https://youtu.be/Vaw2g0tQo58?feature=shared&t=102