They're sometimes necessary for disambiguation. I use them all the time because it's easier than remembering to use them when they're necessary.

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 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.

I always use it. Writing is about communication, so it’s your duty to make sure a reader understands how to interpret what you wrote. That said, when I speak to someone, I NEVER use the Oxford comma.

I'm not a native speaker, but I do prefer using it yeah. In my opinion it reads nicer and less ambiguous. In your example the "butter and tax evasion" otherwise kinda reads like it's one thing. You need to finish reading the following words before you can be sure that it's the "terminal and" and not some in-between "and". But ", and" directly communicates that it's the terminating "and", making reading easier.

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

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.

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.

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

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 use it. It’s nice.

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).

Inclusion is non negotiable.

yall are lucky when I can be arsed to use any punctuation at all

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 don't use it because I enjoy the chaos.

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 use it, since I like it.

AP style guide when i was in school suggested NOT putting a comma in, but also said it doesnt really matter. I err on the side of no comma

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

I use it.

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

Yes. Because it’s the correct thing to do.

😜