Sales of woody ornamentals are down, growers have a glut of large, crowded stock to get rid of. Hence, I am sure, the tall specimens at small prices in warehouse stores. Most look as though dug recently and hastily stuffed into pots, with undersized root-balls.

Leyland cypress is usually root-bound, the stakes on the CostCo stock indicate to me these examples are no exception. On a day to day basis this fast-growing selection should only be bought in small sizes, where there may still be a possibility of opening the roots up at planting time.

I agree with much of the above but to answer your question specifically, a sparse appearance for a young Leyland cypress is very common. Once planted and established in the ground, the tree will fill out appropriately.

Not at all sure that a 10' Leyland in a container is such a good deal at any price, though :-) As fast growing as this tree is, a younger, smaller, less inclined to be rootbound specimen is likely to be a better value in the long run.

The other day I noticed that the CostCo stock of Leyland cypress present at that time had also had side branches pruned back, making it look even more skimpy.

The two warehouse stores I get to the most are CostCo and Home Depot, because I use the CostCo pharmacy. While I am waiting for prescriptions I walk over to Home Depot. Neither outlet is at all good about keeping plants watered in time to prevent shriveling and wilting.