Why is my BezierCurve shaded like a tube? I've added a BezierCurve, and beveled it with a square curve.  The ends are square as expected, but the shading makes it look like a pipe (beveled with a circle).  I would expect a shading more like the cube I've added for comparison.
Because by default is spline set under
Properties Editor &gt; Data Properties &gt; Active Spline as Smooth
When Smooth unchecked, curve become shaded Flat, which means flat also in curvature.

To make it smoother you can increase Resolution U (segment subdivisions)

But in some cases it would be still segmented ... so Edge Split  modifier seems to be better choise anyway :)