I always thought of a cover letter for clarifying something on your resume. Ex: you’re changing careers or industries and out want to clarify why your experience is relevant. So, I don’t do them for every application but in certain situations.
Originally it was to introduce yourself and why you're sending them a resume in the mail. A really good cover letter will get you past HR send your letter and resume to the hiring team. Thst function has largely been replaced by resume scanning tools.
This may be Australia specific, but do job postings not spell out what they want in other countries?
Like, job postings in Australia (these days) are: this is the job, here are the key selection criteria, please provide us a resume and cover letter (or just a resume, or cover letter optional, etc). Even down to maximum number of pages sometimes.
They just tell you, and part of the way they weed people out is if they fail to follow what's written (simple way to weed out anyone paying no attention).
Do other countries just have to GUESS what the recruitment managers want at each company?
I just got an AI to write a cover letter for me highlighting specific skjlls, and then just edited those skills to fit the job I was applying to. Wasn't really that much effort, and I did land a job in about 2 weeks of searching.