I don't think someone should have to work for Amazon in order to write a book about how to become a senior developer.
>> "Senior" will vary depending on the size of company and the scale of problems it deals with.
No matter what company you work for, your role is in a specific context, typically within a group or working on a project. And it's not the scale of problems the company deals with which makes you a senior developer. It's the scope of your assignments and the breadth of knowledge and experience which it takes for you to be able to tackle them.
In terms of pure job title I agree, but it's not the way it is presented here.
This book claims to give you the keys to unlock the skills you need to reach the "Senior software engineer" level.
It doesn't tell you it's not for large companies and it doesn't tell you that the "Senior software engineer" level he is talking about may meet the expectations of one class of company but not the other.
The target is specifically "ambitious" software engineers. I'm fairly certain that ambitious software engineers are many to have FAANGs as a target.
>> "Senior" will vary depending on the size of company and the scale of problems it deals with.
No matter what company you work for, your role is in a specific context, typically within a group or working on a project. And it's not the scale of problems the company deals with which makes you a senior developer. It's the scope of your assignments and the breadth of knowledge and experience which it takes for you to be able to tackle them.