Can I ask what sort of salary range and work you typically offer? It could be many graduates see the big US numbers and expect similar.
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."