So they don't ask where you are staying and what your visa history is-- but they do make you pay $$, right?
Except for the pay money part, I believe you are correct.
It was my belief that the vendors that facilitate applying for the ETA collect are the ones who retain the amount charged (if any money is charged to a visitor) while the Australian government itself doesn't directly see most (or all???) of the money being paid for ETA filings.
Let's see if/how soon the government tries to make the ESTA a fee-required system. I am sure the USG would love to collect the credit card numbers affiliated to even more foreigners than is already in the possession of the government.
