Why doesn't SMS take the traffic channel for free?

There are many apps now, which are very convenient, but they also have their limitations!

First of all, everyone must use the same APP to communicate with each other, which leads to some people not using it, such as the elderly in rural areas!

Secondly, some people don't use traffic, mobile phones are still old machines, and apps can't be downloaded!

Finally, there is the network problem. Where there is a signal, there may not be a network! SMS is irreplaceable at this time!

I believe that with the continuous progress of society and the continuous development of science and technology, the above problems will eventually be solved, and people's communication problems will become more and more convenient and fast!