Coming from Australia to the US I've had a similar experience, but have been tempted to discount it as just familiarity bias that I prefer Australia. But the more time goes on the more undeniable it seems that Australia is a better place to live regardless of any bias I have toward it. So I have begun to embrace that it's just true that Australia is a better place to live.
There's just less day to day friction in life. Taxes are lower (not in the top bracket perhaps, but for almost all people. Even then this sounds false, but add up all the taxes including local and FICA/med and you'll see), and easier to do. Sales taxes are included in prices, there isn't required tipping, speed limits are enforced meaning traffic is smoother and more predictable. Somehow the floor on the quality of goods and services is higher - not choosing exactly what you buy carefully is less likely to result in regret. Democracy is fairly functional. There is lower inequality. Lower crime.
Banking and payment systems are better - no cheques, widespread contactless payments, instant, free interbank transfers. Also, ordinary banks implementing these things instead of requiring outside disruption from tech companies, e.g. apple pay/google pay/paypal.
Healthcare, of course. Interest free student loans and heavily subsidised undergraduate education, such that someone from a poor background can get a good education (I have a PhD now, and my parents have not paid a cent for my education or living expenses during my education). I would prefer university to be free, but seeing undergrads here in the US, and hearing that practically everyone has support from their parents, it's still a big difference. Government payments for students. I would prefer they were higher, but if you live with enough roommates, it can be enough to pay rent.
High minimum wage. Compulsory retirement savings (9%). High salaries generally - if I go back to Australia for the same kind of job I'm in now, the salary will go up by about 30%. Perhaps software development is an exception that is relevant to many people here, but for most jobs salaries in Australia seem higher. Especially at the bottom end. I used to work in retail during undergrad for AU$21 an hour. (pretty much minimum wage plus 20% loading for not having a guaranteed minimum number of hours per week).
Lower cost of living generally. I know if you average over the whole US the cost of living is apparently lower than in Australia, but in the DC metro area where I am now it's not my experience. My weekly grocery bill here about 30% higher than in Australia - and the products of worse quality in my opinion (unless I shop at say, wholefoods, then it's twice the cost as in Australia). Notable exceptions: buying a house, beer, cigarettes, electrical bills, video games.
I don't mean to say Australia and Australians can necessarily take credit for most of these things, though they can for some. There's an argument that Australia is kind of defecting in a prisoners dilemma or sorts, by enjoying all the technological developments made elsewhere without having contributed that much to it. Or that the single-payer system for drugs pays drug companies so little that while they'll accept the price, they wouldn't have developed the drugs in the first place if Australia were their only buyer.
But at the end of it, it's a great place to live.