At a gas station, they have between one and four prices (diesel, regular, premium, and premium plus, or whatever your station calls it). So it’s easy for them to adjust those four numbers. At a grocery store selling thousands or tens of thousands of items, it’s a huge task to set the price tag for each item. So instead (or so I’ve heard), prices tags are produced by the grocery store’s corporate office. This would be much more difficult to do if the price had to vary from town to town. Suppose this grocery store chain has a hundred stores. Instead of making ten thousand tags 100 times, you have to make 10 million tags entirely uniquely. This is even more difficult for things like clothes where the price is on a tag physically attached to the garment. Imagine if the sales tax went down in that town; every single article of clothing would need to be relabeled.
The price tags come on a 8.5x11 sheet, just like address labels. A stack arrives (monthly? Weekly? Not sure) from corporate in an envelope. I'm not sure what happens when the tag gets lost; fortunately those are usually the handwritten signs falling into carts. Price tags really should just be printed at the store.
I doubt if most price tags last more than a month at clothing stores, maybe a year at grocery/other large chain stores. Department stores and trendy fashion stores have too many sales and don't keep the same items in stock year round anyways.
