At a big company, you're getting multiple approvals from multiple people in different areas of the company. If it was as simple as "Get the approval from the President" that'd be one thing, but there's most like a team in charge of just URLs and another team designing the app who would need to go to the URL team for approvals. Another team will most likely be the gatekeeper for whether it goes to production or not, and there's probably at least a half dozen other infrastructure teams I haven't mentioned also involved in the process. I haven't worked for Amazon, but I've worked for another large company, so I know what it's like.

Most of the other teams involved that I've seen at places are usually other development teams who are consulted not because they have any specific reason but because as you go up the chain they want to make sure that nobody is already planning to use that same name/pretty url for something to avoid conflicts where one team all the sudden has two days notice to change their branding/url.