what is the developmental basis for the absence of deep fascia in the abdomen?

Fascia is a general term that can apply to different types of connective tissue.

In the common anatomical usage, deep fascia simply refers to the fibrous connective tissue immediately surrounding (or "investing") skeletal muscle. In contrast, superficial fascia can be simply thought of as the layer of fatty connective tissue that lies between skin and the skeletal muscles beneath.

In the limbs, there are also thickened 'sleeves' of deep fascia surrounding whole muscle groups, creating muscular "compartments", and such deep fascia can be referred to as "investing fascia" or by regional name (e.g., antebrachial fascia for the forearm).   

If one considers the skeletal muscle of the abdomen, it does indeed have deep fascia, although we do not see the same kind of fascial structural compartmentalization as occurs in the limbs.

Anterolateral abdominal (or abdominal wall) muscles develop from connected bands (myotomes) of mesodermal tissue (hypomeres) that grow ventrally from the somites, the bilateral, paired segments of embryonic tissue that also give rise to the connective tissue, bones, and muscles of the vertebral column and back.

Abdominal wall muscles in fact develop from hypomeres of lower thoracic and upper lumbar somites (T7-L1), and this outgrowing muscle splits tangentially into three layers, like it does in the upper thoracic segments.  Thus, we develop 3 layers of lateral abdominal muscles (external and internal obliques and transversus abdominis, just like we have 3 layers of intercostal muscles (external, internal, and innermost).  We can also easily see that the upper external oblique abdominal muscles originate from lower thoracic ribs, beyond where the external intercostal muscles end.

Each of these lateral abdominal wall muscle layers has its own deep fascia.

Some of the myoblasts of the hypomeres migrate ventrally to the midline to form the primordia of the right and left rectus abdominis muscles (AKA,"six-pack").  As the more lateral internal and external obliques and transversus abdominis layers develop, their more distal (ventral) parts become aponeurotic (like flat tendons).  The aponeuroses of the obliques and the transversus surround the rectus, meet at the midline, and the thick connective tissue of the rectus sheath is formed, closing a strong abdominal wall.  Inferiorly, these aponeuroses attach to the pelvis at many points, contributing to the inguinal ligament, and strengthening the lower abdominal wall.

The deep fasciae of the external and internal oblique muscles in fact contribute to the layers of tissue that surround the male testis, which has to descend through the lateral abdominal wall to reach the scrotum, in later development.   The internal oblique fascia and some muscle fibers contribute to the cremasteric fascia, and the external oblique fascia produces the external spermatic fascia.