Arguing for borders seems like it’d be a natural response coming from an Island Nation, so, half a point deduction, there…
But the US’s quandry, is that we desperately need immigrants but the current theme on one side is “get rid of the immigrants!”
Being angry at the people who are going to save our nation from 2nd-rate status should be treated a bit better.
Australia definitely is a big island with 'easy' borders to control; but the strict guarding of borders happens in many nations around the world that are not islands (in Middle-East, Asia) .. e.g. certainly China/India .. but also e.g. Japan/Indonesia. Border control is all about safety; otherwise you can be simply run over by unwanted/dangerous individuals.
You're mixing up the concept of migrants and illegal aliens. Like the USA, Australia has many migrants each year (the Government thinks the country needs them). But it has very few illegal aliens - a sane country will permit migrants that meet all migration/visa criteria but keeps unwanted migrants applying for a visa out. And by that concept any illegal alien cannot be tolerated as they will in all likelihood not meet the desired criteria.
If the USA needs migrants to work on farms the proper procedure is for the employers to apply for work visas on behalf of their prospective employees/future migrants. Immigration then checks whether the visa application meets actual criteria, and whether the prospective employee/migrant meets the minimum requirements (health, language, criminal history, etc.) and seems suitable for the job.
That is how your arrange safe and sufficient migrant employees if they are genuinely needed on farms/factories. You prevent 'scam' work-visa applications by rogue employers, and you can keep unsuitable or criminal job applicants out.
Allowing illegal aliens to work on farms/factories without checks/balances creates a grey-zone 'underclass' without any rights (so very vulnerable to exploitation by employers - I've witnessed this myself); and causes unwanted individuals to migrate as well and endanger safety in society.
Another obvious advantage is that when allowing Immigration to properly assess/approve any work visa application the Government can monitor whether the country's capacity for housing and health (e.g. hospitals) keeps up with resident nrs. So you avoid the situation where migrants en masse move in and then create a housing/health crisis.
It's all common sense really - and this is standard practice in many countries around the world (not just islands).