three-note beams inconsistent

The beam angle in (at least) three note groups is inconsistent, as shown in the attached image.

Space-to-space groups have a shallower angle than line-to-line groups. Compare the top staff with the third staff.

Subjectively I prefer the shallow angle (which Gould concurs with), but what really grates is that the beams are not parallel even though the angles of the notes are.

It seems that the line-to-line beam exactly follows the notes, but the space-to-space beam doesn't.