Turn restrictions are to prevent vehicles from making turns. There are a lot of routing softwares that use OSM data to route individuals through cities like Buenos Aires. Turn restrictions are necessary in order to ensure accurate routing. The turn restrictions I have added were based on road paint and some signage. We recently conducted a ground survey of Buenos Aires and the footage should be available on Mapillary soon. Older Mapillary footage shows turns being allowed at some of these intersections but new imagery shows they are not allowed.