On most solar farms, the panels only cover about a sixth of the land area, or less. The rest is taken up with accessways between the rows of panels, and roads around the outside. Check out some photos, for example https://energy-cc.co.uk/wp-content/uploads/2020/09/Benbole-S...
The reason the rows are widely spaced is to minimize shading by a row of the one behind, when the sun is low in the sky.
With the panels being flat on the ground there is no shading problem. Laying them side by side eliminates the gaps and they plug together so there is no wiring to do. Omitting the racking eliminates its cost, the time to install it, and the wiring between rows.
A SIXTH? I don't see how that can be necessary. They might use that much land because it's worthless desert or something like that.
Where I am there is not exactly a solar farm, but there is a maybe half megawatt array on a flat canopy over a parking lot. This is in an area of expensive real estate, and there is almost no wasted space.
As for spacing to avoid shading when the sun is low, obviously that is an optimization problem and in all likelihood they have worked it out. Don't forget that when the sun is low, the flat array produces almost no power.
The reason the rows are widely spaced is to minimize shading by a row of the one behind, when the sun is low in the sky.
With the panels being flat on the ground there is no shading problem. Laying them side by side eliminates the gaps and they plug together so there is no wiring to do. Omitting the racking eliminates its cost, the time to install it, and the wiring between rows.
Etc.