My whole family uses Siri—both through our phones and through the HomePod mini in the kitchen—to add items to the shopping list.

Siri occasionally misunderstands the name of the item, or needs to ask who's speaking (when on the HomePod), or has trouble because the phone of the person asking has briefly dropped off the Wifi, but in the ~5 years we've had it, I can count on one hand the number of times adding has just failed with any pattern remotely like what you describe.

For me it's 80% accurate (including sometimes I'm entirely surprised it heard above all the screaming and howling) and then 20% it's just hilariously horribly wrong.

Let me guess, you have an American accent?

Well, mine personally shifts frequently to British—but yes; I can see that that could cause a problem for some people, especially if their accent is not a specific one that Siri's been trained on.

As a Brit, let me tell you, there is no such thing as a British accent. Our accents vary wildly by region, and sometimes those regions can be under ten miles away, let alone the huge differences between the four home nations. My own is basically what Americans imagine an English accent to be, a bit Hugh Grant but not as posh. Siri can do the basics for me, but playing some random song when any of us have asked it to do something completely different has become a running joke in our house. It's great when the kids try to set a timer or something and it suddenly starts blaring out some very sweary hip hop.

Oh, certainly—mine is vaguely East Midlands, as that's where my father comes from. But without knowing that the person one's talking to is British, just saying "British accent" is going to be much clearer.

Very true - and when I'm in the states mine is always referred to as a British accent. Or people think I'm Australian.