Question
Moved into a new construction home last July in Dallas TX. My lawn seems to be struggling quite a bit over some of the neighbors. After aerating recently, I punctured holes and caused countless leaks in the dripzones in the parkway. This is the section between the sidewalk and the street about 4 feet wide. The city code states you must have drip zones for irrigation in parkways and ALL front facing flower beds. No spray. Anyway, the parkway was one of the primary struggling areas of lawn for me. When working to repair the first several leaks, I discovered that below the sod was about 6 inches or so of sand. No soil. Is this why I may be struggling to grow a healthy lawn in comparison to some neighbors. We must assume all other things equal (appropriate watering, feeding, mowing height, etc.)

Answer
The short answer is "No". But let me ask you this; do the roots of the grass go into the sand at all?
If they do, it means that at one time the conditions were right for this.
These roots that go into the sand; are they alive (white) or dead (brown)?
If they are alive it could mean that all other conditions are right except nutrition. You might wish to apply some fertilizer - quickly. There might be regulations about fertilizing during the months June to September.
If the conditions were favorable and the sod roots did not penetrate the sand layer; or they did and died, then something in the sand might not be good for roots or their development.