AFAICT, you've got it mostly entirely wrong. It's not "are not allowed except for very specific reasons". Instead, businesses CAN "refuse service except for very specific reasons" (at least in Canada and the US, didn't search laws for Australia, but I doubt they will differ much).

https://www.quora.com/In-Canada-can-a-business-refuse-the-right-to-provide-a-service-to-anyone

In Canada a business has the right to refuse to business with anyone, UNLESS they do it for reasons of “race, national or ethnic origin, colour, religion, age, sex, sexual orientation, gender identity or expression, marital status, family status, genetic characteristics, disability and conviction for an offence for which a pardon has been granted or in respect of which a record suspension has been ordered”, in which case they would be in violation of the Canadian Human Rights Act which would make them liable for prosecution and/or civil proceedings.

https://www.nextinsurance.com/blog/right-to-refuse-service-to-rude-customers/

What is the constitutional right to refuse service?
According to the Federal Civil Rights Act of 1964, no business serving the public can discriminate because of a customer's national origin, sex, religion, color, or race. This applies even if it's a private business.
The Americans with Disabilities Act prevents a business's refusal of service based on a customer's disability. It prohibits discrimination in employment, transportation and public accommodations (such as stores, restaurants and most businesses.)

So it is entirely legal for a business to discriminate against someone who hasn't take the Covid vaccine.

I found this out after a 2 minute search (true it matched what I already was virtually certain to be true, but still it didn't take long to verify). What is your source for a contradictory stance?

In any event, anyone who believes in individual freedom should support that right. As an extreme example, do you think a business should be required to serve someone infected with Ebola?