That's an excellent question. Adoption rates in many territories are around 20%. Even if an application were mandatory, there would be ways for the population to get around that, such as not using a phone. This brings us back to reality. In my opinion, there has to be a voluntary side to the use of the application.
In this context, how do we increase the adoption rate? It would be by having conditions that foster trust. We need a system where privacy principles are accepted. I think transparency is also very important.