What do you mean by coding?
There are tools for BMWs (and Minis) that allow to override some settings and enable some features that are not offered on a specific market. You will need a ~$20 OBD cable and an app to code your changes. For instance, BimmerCode [1] has samples of what could be changed on their website.
Flash or NVRAM configuration change using some CAN bus software (often manufacturer specific).
It's to do with the EPA rating. If the car maker allows auto start/stop to be turned off permanently then the ratings agency will test the car again with it turned off then combine the two results into their score. Having a slightly worse EPA mileage across their fleets is probably bad for sales and pleasing governments
I don't think there is a regulatory requirement to keep it enabled. I have a fresh one ('23) and it remembers my last selection. The previous one I had to code to force it remember my preference. If it is that annoying consider coding - it got ridiculously easy to do.