It could be a cost issue. A chip that collects data from connected sensors and sends it via Wifi is small and cheap. Adding a display and buttons ads size, complexitiy and costs. Therefore manufacturers offload the interface to an app and a device you already own, and they can update without expensive recalls.
If the task or device is more complicated and the device would also need it’s own storage, CPU, display, sound etc. the product costs could go up by hundreds of dollars, depending on functionality and how many units they plan to ship.
I also hate apps. Still have my 2010 smartphone in a drawer that still turns on, however it;s useless because google playstore, maps and email now used an more modern SSL standard that this phone does not support anymore, and it won’t receive any updates. I expect the same will happen to a lot of devices that are controlled by apps when the manufacturer decides he won’t support it anymore, or Google breaks the app because some new protocol must be supported now that didn’t exist 2 years ago when the app came out.
They can use your wifi signal as a beacon by triangulating the signal strength from at least 3 different points. Then they can figure out in which departments you spend the most time, how long you spend in store, heatmaps, which aisles you skip and generic info like what time you visit, which locations you also shop at.
A quick google for “Retail Wifi tracking” brings up mirame.net , where you can see some of the features.
I would suggest to set your phone to flight mode if you see a “free wifi” sign in your shopping mall.
Skinner.meme: “Should we build sensible, small cars that are cheap to buy and drive, dont support speeding, need little parking space and prevent horrific high speed crashes? - No, it would hurt the economy and my penis would fall of driving something with less than 400HP that dosn’t make vroom-vroom noises!”