[johnnyanmac]

If I had to take a guess, it's more about policy than "they don't catch them". I doubt it's someone coming in, taking a TV and walking out.

It's more like if an item or 2 "sneak in" and the checker just lets them go. It'd cost more money in congesting the line, grabbing security, etc. to contest that item than it would be to just let them go. They don't want to press charges on someone who spent $100 because they wanted to sneak some $15 pills by. All stores expect X% theft anyway and build it into the price of their item (or secure it better if it's a small, often stolen good, like tech).

It's probably a cultural choice, though. Meanwhile, the Walmart down the street is much more aggressive on that stuff.

[sneak]

Victims don't decide who is charged with theft.

"Pressing charges" isn't a thing.

[iinnPP]

Depends on where you live.

Seeing as Costco exists in Ontario, Canada. Where citizens with knowledge of a crime can use private prosecution.

https://www.ontario.ca/page/private-prosecutions