Google’s products and services are used by a lot of people on a daily basis and it is one of the appeals of using Android because these services are integrated better compared to on iOS. Google knows this which is why they usually have a set of requirements that phone makers have to meet in order to be able to preload these apps on their devices.
However it seems that Google is about to make things a little harder. Prior to this, phone makers who did not submit their request or have their request denied could still preload these apps, but it looks like Google is changing that where they will verify a device first. If a device has not been verified, they will then block Google’s apps from running on that handset.
While this is good news as it means better control over quality and ensuring compatibility, this has presented a problem to users who run custom ROMs. Given that custom ROMs have nightly builds, it makes it difficult for Google’s apps to run on them. However thankfully Google is aware of this and is providing a whitelist to users to submit their Android ID so that Google apps can run on that ROM, something to take into consideration if you’re having problems running Google apps.