AFAIK basically (A) Once you get PR you never have to apply for another visit visa, a process which itself is tedious and expensive if you were previously making sporadic trips; (B) You can access social services such as (internationally speaking) very high grade dirt cheap public medical care and potentially perpetual but qualified access to social services payments ("the dole"); (C) You receive discounted access to local education; (D) After another 4 years you can obtain citizenship and voting rights. (E) As an adult migrant you receive hundreds of hours of free 1:1 spoken English training.; (F) You have additional rights under law such as additional support for any prudent claim of local tax residency should that be a foreign jurisdiction's pressing concern.
So all up, not that unreasonable. Although, it is a hurdle for many people, including lots of Sydney Uber drivers I've had lately.
Full disclosure: Have done this for Oz (I recall more like AUD$8K but that was a few years back), currently going through US non-immigration visas in prospective immigration as an entrepreneur, it's a PITA. Spoke to the HN immigration lawyer dude last year. Despite good advice, our situation is not helped by certain relevant websites running on Salesforce and being down, Chrome-only, nor by 3-4 month post-COVID wait times for certain non-immigrant visa interviews required by immediate family...