Someone steals $500. What do you do?
Charging someone alone costs thousands.
Putting them in jail costs tens of thousands per year and has some serious negative externalities (what happens if they have kids? what if this knocks them off the economic treadmill and they're forced to continue stealing as the only option to them?)
And then you have organized crime organizing hundreds of people to commit the same petty theft. But they're hard to find and catch.
I think the resolution won't be laws changing, so much as stores changing to be harder to shoplift from. Already places are experimenting with more of a fast-food style order at the front on a tablet, and the clerks will bring the goods to you from the back. Or a shift to more of an online ordering world, where shoplifting is close to non-existent (though package theft and credit card fraud are problems).