Once upon a time most fabric you bought was torn rather than cut. Tearing fabric should be accurate, but both ends need to be torn so you have the straight grain on both ends.

Often Walmart clerks are put wherever they are needed rather than where they have been trained to work. I feel for them sometimes because they are caught between a rock and a hard place. Situations like this are poor management issues but it makes for disgruntled customers regardless of the reason.