Airline 'travel pass' app will show COVID test results, vaccination

This is no different from now though - any airline you fly on, or hotel you stay in, has your passport info on file.

True, not all. However, the majority of hotels/domestic airlines will ask for a passport from a foreign national, though depending on the country, if you happen to have a local driver's licence or sometimes even an Australian driver's licence, that is often accepted too. For countries, as an Australian citizen you will need a passport to enter EVERY other country, including New Zealand. The only exceptions to the passport rule are specific situations like

1) EU/Schengen nationals travelling within the Schengen passport free travel zone (they can use their national ID cards or some other equivalent instead);

2) citizens of the USA/Canada/Mexico and several Caribbean countries travelling within each other's country for short trips; however, a passport has been required for several years now for travel by air and even most land based travel too. A border crossing card is acceptable for short hops across the US/Canadian/Mexican border by citizens of these countries last time I checked but this may have since changed.

3) citizens of various countries in Asia (possibly Africa/Latin America as well) travelling across shared borders on day passes/short term passes (aka border passes). These passes usually only permit travel in a limited radius from the border, and typically the holder must return through the same border crossing as the one entered. I don't know how it works in Africa or Latin America, but in Asia I'm very familiar with the process.

A Thai national for instance can use their national ID card (or another acceptable document) to make a border pass that allows them to cross to Myanmar from Kanchanaburi province and travel to Dawei and surrounding areas 150km away, spending 2 weeks there. They must return the same way they came and technically aren't allowed to travel to other cities. Heading north, there is a checkpoint where they will be stopped if they try. Other crossings have similar rules, although some limit travel further. A Lao national travelling to Thailand, China, Cambodia or Vietnam will find similar rules in place - they may be able to spend up to 3 days and 2 nights on a border pass or sometimes longer and limited to a particular province or two in the neighboring country. Only a passport allows complete freedom of movement throughout the country and using a different border crossing to depart.

For hotels, I don't see it happening for small, family owned hotels or motels though. Perhaps the big 3, 4 and 5 star international chains like Marriott, Ibis, Sheraton etc. will. AirBNB might impose conditions of their own. I checked the other day and apparently there is now a policy where both guests and hosts must wear face masks as a condition of interaction. I don't know how they enforce this, but strictly speaking this applies worldwide, even in the few jurisdictions where face masks are not mandatory (such as Sweden, Belarus, Australian states/territories except Victoria and Adelaide and a few others). So if AirBNB can impose a face mask requirement, I don't think it will be difficult for them to require this sort of pass in the future.