Trying to learn Ionic3/4 - can someone explain why the URL doesn't change with this project?

I have been using Ionic 1 for years and I am slowly trying to teach myself Ionic 3/4. I have very little experience with TypeScript, so I like to look at other peoples code and projects to try and follow the logic. I have been using this project lately for some self-paced learning and I have a question as to why the URL doesn’t change when the project is served through the browser.

Project:

Typically, as you move from tab to tab, or from view to view, you would see the URL change as you move through the app. In this project, the URL stays the same.

Is this something that is configurable, or did the author just take a different approach when designing the code?

Thanks for any info or pointers.