They're expensive because they're inefficient. To accomplish them efficiently is ambitious and elegant without a doubt.

A startup that can chip away at what makes these things so inefficient is going in the right direction. Looking for inefficiencies, such as with present day email, is a good way to find a direction.

Economics is still at its heart the study of the problem of scarcity. Economies, and all economic activity, attempt to alleviate or manage that problem.