The forthright Sam Denby of Half as Interesting explains why soda cans in Hawaii have extra ridges around the neck and a larger circumference on top, unlike cans in the rest of the US. As it turns out, this had been the US industry standard for many years until ~1998, when it was discovered that the cans could be made more economically with a smaller lid.
The Hawaiian lids—known as 206es—were actually the industry standard for a while, …the aluminum in a can’s lid is more than twice as thick and uses more than twice as much material as the rest of the can, making smaller lids a great way to cut your can-ufacturing costs.
Hawaii never changed its standard because of distance and expense. Plus, its beverages are locally bottled.
…in a market as small and remote as Hawaii, changing all the equipment in the can factory, not to mention the bottling plants to suit the smaller lid, is just too expensive to be worth it. So rather than invest in overhauling the entire archipelago’s can infrastructure, Hawaii just sticks to the 206es.