Why can't i get near sighted eyeglasses in stores?

Not accurate: Glasses in the store are meant for people who do not have a significant distance prescription. Nearsighted people may not have the same prescription in each eye and may have some astigmatism. This variability means that generic glasses would work for only a very small percentage of them.

Too many options: Stores carry reading glasses because these come in discrete steps with few possibilities. An inventory of near sighted glasses would require hundreds of eyeglasses to cover the most common powers, and that does not include the need for astigmatism correction. So glasses for these needs are fabricated through optical shops due to this complexity.