Does google check any OS security algo before installing it's app as inbuilt apps? Is there any authority which checks OS for illegal activities?

Does google check if the OS is not doing any illegal activity before installing it's app as inbuilt apps?My doubt is that is it possible for the certain company to modify the next OS update in such a way that it will allow them to send all the data to a particular server?Is there any way/authority to check this?

Thanks,Rahul Gunkar