Now there is a method called Isogeometric Analysis (IGA) that was meant to improve this. It uses NURBS functions (just like CAD) for the shape functions of traditional FEM. The idea was that now, if you have NURBS describing the CAD geometry you can skip meshing and just directly calculate on the real geometry. But it did not catch on. The reason being basically, as far as I remember, was that most CAD geometries of interest are not pure NURBS. But they are operations of NURBS (think cube minus some other cube - trimmed surfaces). And IGA has problems with that.

This is a problem that openSCAD will probably also not be able to overcome. Maybe at times it might be easier to create NURBS geometries without trimmed surfaces. But most probably that cannot be done in most cases of real world significance.