He wants me to get a job, but work in Australia is pretty ridiculously difficult to find at the moment,
Don't make excuses, just keep working at this. You mentioned below you've sent out a dozen resumes a week, for an entire year. That makes about 600 resumes. Show him proof that yo'uve sent out 600 resumes, give an EXACT number.
For someone with a lot of money, it's confusing to me why he would begrudge me the fact that I'm still living at home.
You're... basically a child, so I don't blame you for having this attitude - but it is a shit attitude. Entitled, lazy, unmotivated, all the things your dad is afraid of seeing in you is described by this sentiment.
The issue is that you're missing the damn point. The point isn't that you're a financial burden. The issue is that you have done nothing in your 18 years of life to prove that you're capable of being an adult. You think being alive for 18 years makes you an adult? Because you're wrong. You have to prove yourself. Getting a job, and an income and supporting yourself - heck, even WANTING to support yourself, THAT shows you're an adult. Having a birthdate pre 1997 does not.
I would understand him being annoyed if I sat on my ass all day and didn't do anything or make any attempt to find a job, but I am.
Ok, so supposedly you don't sit on your ass all day:
I'm starting a course that's 5 days a week soon,
Soon is not now.
I'm doing work experience where I basically have to set up an entire company's website,
How many hours a day does this take you? Are you out of the house when this happens? Do you take frequent reddit breaks while you're 'setting up a company's website'? How long have you been on this project so far? Anything to show for it? Show him that. Maybe with daily progress reports.
and I'm still doing an hour of chores every day.
So far, you've accounted for ONE hour of chores every day. That's the only 'evidence' you have of not sitting on your ass all day.
You keep a daily log of what you do? Describe the last three days, TO THE HOUR, of what yo'u've done. Tip - this is standard practice in many professions, so it's not unreasonable.
Finally - you've been at this for a year, with no results. I do not live in Australia, so I don't know your situation - but do you know of other 18 years olds who have gotten jobs? Where did they get them? What did they do that you haven't done?
You said your family is wealthy... Well, can your dad hook you up with a job? Have you asked him?