Trains run in these places, but services are poor for a variety of reasons. Either timetables are not coordinated at the border (a service arrives one side a short time after the onward service has already departed), or the service is otherwise spare or thin, or only certain categories of trains run.
In these cases it would only require a little coordination between railway companies and public authorities either side of a border to fix the problems.
Please use the links in the menu for details of the individual borders.