A lot of these pharmacy stores are setup such that the checkout is offset from the entrance/exit probably because most of the money comes from the pharmacy. It also means that shoplifters just go straight out carrying whatever they can grab and at least in my area they aren’t even trying to be discrete

Then why don't the stores just hire people to stop them?

Stop them from doing what? The police won't prosecute. Security guards are private citizens and do not have an unlimited right to just grab other people and detain them. If the stolen goods are inside, say, a backpack, they also do not have the ability to search that backpack.

You can only have security guards if the state backs them up. The state is not backing them up.

> Stop them from doing what?

Leaving with things they did not pay for.

> Security guards ... do not have an unlimited right to just grab other people and detain them. If the stolen goods are inside, say, a backpack, they also do not have the ability to search that backpack.

Not unlimited rights. They can use reasonable (and solely nonlethal) force to detain shoplifters that they have probable cause are shoplifting and even search them (for instance, their backpacks) for such goods. You need to read up on California Penal Code 490.5.

They cannot punish them, but they can prevent them from leaving with items they don't own.