Always use it.

If I’m listing this, that, and the other, the commas are just a horizontal series of bullet points, so there should be a comma for each item in the list.

Nobody would go:

• This
• That
  The other

I was always taught to never use it (UK) - but will use it where there might otherwise be the risk of ambiguity

I use it because it feels like otherwise you are lumping two things together. In your example it would be butter and tax.

Another example could be talking about people:

I’m having Jim, Frank, Ian and Susan over for dinner.

Without the comma I feel like that implies Ian and Susan are in some kind of relationship.

With food:

I had pickles, bacon, ham and cheese for lunch.

That seems to me like someone had a ham and cheese sandwich versus ham and cheese separately.

https://www.smbc-comics.com/comic/oxford-comma

Eh, in casual situations like this, it depends on if the , registers or not. I’m not wasting attention to go back and add one.

But otherwise, as useful. It helps clarify the difference between ands. Some ands are used to connect two things in the entire list as a unit, so when that is a factor, it helps.

I want to be able to communicate both ideas:
https://i.kym-cdn.com/entries/icons/original/000/017/771/the-oxford-comma_52c855ed979ed_w1500.jpg

I don't use it because I enjoy the chaos.

It makes more logical sense to use the serial comma in this example. Bread, butter, and tax evasion are three separate things. If you leave the comma off, it becomes "bread, butter and tax evasion" suggesting that the butter and tax evasion go together with each other. Give me some butter on my tax evasion, please.

Yes. Things feel out-of-balance without it to me. However, if the meaning is unclear (something something stripping Hitler and Stalin), I will work around it and/or use other punctuation. I think I have a bit of a weird synesthesia thing going on for written text (English or written code (in the programming sense); I don't have it as much in the other languages I read/write, but it isn't absent there, either).

I tend to use it, but also Who gives a fuck about an Oxford comma? (or more seriously) So I don't really care or usually even notice if others do, since in 99% of cases you can understand from context what someone means, and if you still don't, you can ask (and have a little chuckle together at a possibly absurd result to the omission)..

I was taught in school (UK in the '90s) that putting a comma in that spot is outright wrong. As an adult I realised it is much clearer and always use it.

Inclusion is non negotiable.

I’m not a native speaker and was taught not to use it in middle school.

I'm a technical writer (aircraft maintenance and flight operations manuals, mostly) and eliminating ambiguity is key to clear, effective communication.

Leaving out that comma takes a sentence with only one possible interpretation and gives it several options instead.

Yes.

I use it.

Only way to avoid travesties like the famous "I want to thank my parents, Margaret Thatcher and God."