https://medium.com/flutter-community/a-deep-dive-into-flutters-accessibility-widgets-eb0ef9455bc

Many mobile users have visual, physical or age-related limitations and these can prevent them from seeing or using a touch screen. There are also users with hearing loss, which can leave them unable to hear notifications and other audible alerts. According to the World Health Association, more than a billion people are living with some form of disability; and between 110–190 million are not able to complete their daily tasks because of the challenges they face (source). Technology can have an incredible, positive impact on these people’s lives if designed properly. It can empower those facing these challenges, enabling them to be more productive and independent.

Not all mobile users are going to interact with your application in the same ways. Therefore, it’s important to make sure your application is accessible to everyone. Implementing accessibility correctly can enhance the quality of your application, increase your number of installs and strongly impact how long your users are going to stick with you.