Why has Australia made it impossible for Americans to visit?

Australia now requires U. S. citizens to apply for an ETA, and the only way to do this is through a defective app, as you can see here from the app reviews.

https://play.google.com/store/apps/details?id=au.gov.homeaffairs.eta

They've basically made it impossible for U. S. citizens to visit the country. Why? What have we done?

Why has Australia made it impossible for Americans to visit?
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