Clicking buttons on a mobile device is quite a chore. You can understand what users go through if you break down their experience.
All buttons on mobile interfaces are targets that users have to hit with their fingers. For each interaction, they must locate the target and tap it accurately. Not only that, but they also have to apply the right amount of pressure to the screen for the touch to register. Therefore, many elderly users struggle with clicking buttons.
However, the average user also experiences issues with button clicking. They often have to move their finger to different screen areas to hit the targets. This movement of targets causes them to look around the screen to search. Not only that, but they also have to use two hands to hit targets that the thumb can't reach.
For instance, this interface has a "view all" button that users must click to view the complete list. For some users, that's a tiny touch target to hit and can even be hard to find.
