Why is that? There can be country names in movies titles... (I get 12 movies when I search for America for example using all titles filter)
"America" is not the proper name of the country, and there are very few titles containing "United States of America." A title is more likely to contain "USA," but that could be the country or part of another word. A search can also be restricted to [Title] or [Original title]—probably a sensible thing to do if searching for a specific title that contains a country name.
But all this is beside the point. Surely the purpose of the field is more than just a means to generate more search hits. Much of the meaning of the data is lost by omitting this additional information. And it's not just the country in which the title was used. AKA's also include working, pre-release, complete, dubbed-version, DVD, re-release, and regional titles. Sometimes a title will be different than that used for a release in countries of the same language (e.g., British and North American releases). Or there may be multiple titles for one country (e.g., English and French versions for Canada). The various titles themselves can be meaningless without some indication of how they were used.
Even so, if the country is added to the aka field with brackets, it would be possible to enter into the search field the country + space to clear the search results from the “wrong” search results.
This occurred to me as well, then I realized there's more to it than just a country. And it's the additional information that's in brackets (e.g., "USA (working title)" or "Canada (French title)").
It's probably not possible, but it would be nice if the data could be retrieved/stored as "Title ... Country (additional information)" and displayed in the same manner as "Actor ... Role." But setting it off with a " • " or enclosing it in square brackets would do. Also, many of the entries include "(imdb display title)." I doubt this means anything to a PVD user and should be omitted.