Pro tip: pay cash whenever you can. You can avoid a kiosk that asks you whether you want to tip 30%, 25%, or 20% for the $8 coffee you just bought and just throw some loose change in the jar.
I am increasingly doing this as I have started to see "we are a cash-free business" signs; I don't want to lose the option of paying with cash, so I'm starting to exercise it more often.
As the government pushes us towards a cashless society. Australia is on the brink of going cashless, so your solution would not work.
Australia's government has over reacted and over reached since March of 2020. A backlash is inevitable.
I get thousands of dollars back from my credit card company every year and pay for everything I can with my cards. Many cards specifically give you a higher percentage back on restaurants. I have no intention of ever giving that up. The awkwardness at the counter when the tip prompt shows up is only in your head.
You know that paying with cash is effectively an automatic ~3% tip over paying by credit card, right? You are getting a cut of the service fee they charge the restaurant.
I do not trust a company bribing me with my own money.