@Melinda255 In case you aren't aware, Airbnb is an international platform, with guests and hosts and listings all over the world, so whatever you consider to be the "American way" is irrelevant.
As for what you call discrimination, discrimination refers to something which is part of who a person is that does not involve choice- the color of their skin, their age, their nationality, their gender, their sexual orientation, a disability.
Getting vaccinated or not is your choice. As with all choices in life, they have consequences. You do not have a "right" to stay in someone's home if you aren't willing to comply with their house rules, which they have for the safety and comfort of themselves and their guests.