HTML5 video autoplay behaviour is not consistent across similar Android devices

The autoplay functionality does not seem to work consistently across devices for me. I have tried this page: https://googlechrome.github.io/samples/muted-autoplay/ on three different devices with mixed results:

1. Samsung Galaxy S7/Android version 8.0.0 - videos autoplayed fine
2. Moto G6 play/Android 8.0.0 - videos did not autoplay
3. Samsung Galaxy Tab A/Android 7.0 - videos did not autoplay

I assumed that the videos not playing was due to the lack of user interaction as documented here: https://developers.google.com/web/updates/2017/09/autoplay-policy-changes

But i technically didn't interact with any of them, other than re-loading the page. I also checked in chrome://flags and all 3 devices had their autoplay policy set to default, which means that default is behaving differently per device.

Any light you could shed on this would be helpful.
Thanks.