Sorry, that is not true. The border controls exist and are happening right now. Austria does checks on "Berg" border control station. Hungary, Czech republic,Poland does checks of hgvs transporting animals, due to the current cow disease spreading.

Just because the border control police does not stop all cars, it does not mean they are not there. They may stop you any time so that information in OSM is useful.

You can see the same problem (removing barrier=border_control) is discussed in Czech OSM forum at https://openstreetmap.cz/talkcz/c4061#map=8/49.799/15.439&layers=d and they do not agree with it.