> why someone did not solve the problem already?

Most Americans are fine eating stale or preserved bread. (Almost all pre-sliced supermarket bread is the latter.) You just don’t have enough people to spread the cost of baking fresh bread throughout the day outside wealthy communities.

That said, a lot of European bread is also trash. There are simply some bread-loving ones where it isn’t. Similarly, there are places in America with great bread (New Orleans, New York and Miami), and places without (Northern California and the Midwest).