But if its pays poorly, and consists of IT/database management/code-monkeying another app/help-desk, then one understands why one mainly gets immigrants applying (because they're desperate for the job, are relatively unlikely to be discriminated against, and they meet the qualifications whereas australians can get better wages elsewhere for easier positions).
Honestly, I'm a bit dumbstruck by notions of a shortage of tech supply in australia. Comparatively we've got very little on the demand side, outside of a handful of big-corp IT departments (who have off-shored a lot of work to china/phillipines/india/etc) and IME we often pay relatively poorly...and government policy in terms of security/IP/storage/privacy etc is 'relatively' hostile towards the tech sector and driving firms offshore...
The E3 visa is similar to the H1b but it’s far easier to get because it’s Australian only (and now Irish too, iirc) and we only use ~3k of the 10k/yr quota. Getting one simply requires a standard 4 year degree, of which Software Engineering qualifies (what most institutions call the Comp Sci equivalent-ish degree in Aus) and a 5 min “interview” at a US consulate somewhere outside the US.
Source: Am Australian that moved to the US temporarily to work on an E3 because Australian tech companies simply don’t pay competitively.
Eventually I decided to bite, and responded back to a recruiter. "Why are you contacting me, I'm not in the Oz"
The answer was along the lines of the parent comment: "good technical hires go to London or San Fran."
I had a similar experience when I graduated over a decade ago. My first gig was working for one of the big Indian offshorers - I actually spent a year in India, which was interesting. Regardless, after a few years on similar crappy contracts with over-worked, poorly compensated, indentured servants from India, who were tied to their employer via an H1B visa, I came very close to quitting software for good and going to law school.
Luckily, I found an industry that cannot use visa workers and have been able to make a successful career with working conditions and pay that's fair.
The visa system has turned most software gigs in the US into a very bad deal where ageism, long hours, lower and lower pay, and general working conditions get worse each year. Then they wonder why smart kids in college decide to go into law and finance, instead of STEM.