The OP said he was hitting the button. In other words he was turning it off. I don't have a 16. I don't know if it's a toggle on/off switch. Or if once you hit it it stays off until you restart the car.
If they give you a way to permanently disable that function. They can't use it to raise the EPA mileage rating. Everything is about mileage ratings these days.
There's an On/Off button right below the shifter. The system always reverts to 'On' when the car is turned on, regardless of whether it was 'Off' when the car was shutdown prior.
If you press the Auto-Start button, the screen between the tach and speedo informs you that the feature is disabled. After a few seconds, that screen goes back to whatever it was before (SH-AWD graphic, MPG display, Oil life, etc.). Also inside the tach there's a small light (similar to a check engine or brake light) that stays lit indicating the feature is deactivated (If I recall, it's am amber A with the arrows above it and a cross through it showing it is crossed-out or deactivated). It's VERY intuitive in regards to the car informing you the system is off. When the engine is auto shut-off, the same logo lights up in Green without the slash through it. All that said, the system is SUPER simple and it's very intuitive and easy to tell if the system is on/off, etc. So the fact that it's so obvious and the OP has issues, does make me think something might not be right with his car.
If the OP has found a way to permanently disable the feature, that might be worthwhile.
I have found that when it is SUPER hot (in Texas), the system is less likely to activate, and when it does, it only stays off for 10-15 seconds before re-firing the engine. I've exhibited at a reasonable length red light that the engine will shut off, turn on, shut off again on its own before the light turns green. Finally, I've also noticed that when the car is first started and the engine is cold, the system almost never activates. Cars warm up fast in Texas Summer, but for the first handful of lights, it generally doesn't work.
In regards to the defroster, interestingly enough, when I use the Engine Remote Start, when I get into my car, I always notice the defrosters are on. Even after starting the car intentionally when I'm about to drive, the defrosters stay on (which is kind of annoying). When it's 100F outside, I don't need my defrosters on, and it doesn't seem to shut off. I understand that the car in the winter should turn the defrosters on, but it'd be nice if the system realized it's 100 degrees and defrosters aren't necessary (or perhaps it uses the defroster to override auto start/stop???). I do assume that like most cars, after 10 or so minutes, the defrosters automatically turn off. I haven't tested that theory as I've only used auto start/stop a handful of times and each time I catch it within a few minutes of driving.