At first, let’s talk about mobile network.
So what is truly unlimited? Truly unlimited simply means that user can access as much high-speed internet as they want. But in mobile network plans, the data is unlimited but it provides high speed until you reach the high-speed data limit. For example, take a look at the image below.

As you can see in this image the following Jio mobile plan says “Data at high speed (Post which unlimited at 64Kbps)”.
So as I’ve said before the data gets slowed down at 64Kbps after reaching a certain limit. In this case which is 2GB.
Now, let’s talk about Broadbands.
Unlike mobile broadband plans are truly unlimited. Take a look at the image below.

As you can see in this image the following Jio fiber plan says “Truly Unlimited” in the data section.
Now why this happens?
In the case of mobile network, it is wireless you can take it with you everywhere. But in the case of brodband network, wires are required so you can’t use it anywhere except your home or office. But if you want to use mobile network then, a tower is required to make it wireless and to be used everywhere. It won’t need that much money to repair and maintain wire than a tower.