The answer to this question is quite simple, because Google (excluding the Pixel line) isn’t making the actual phones, just the software. The actual manufacturers (Samsung, Motorola, Huawei, etc) are taking Google’s OS and putting it on their phones. This case mostly hinges on Googles behavior being monopolistic to them, not to the end consumer.

On the other hand, Apple make both the OS and the Hardware, there’s no manufacturer they’re forcing the app store on, so the same rules don’t apply here.