If all businesses discriminate then there is an opportunity to compete using no discrimination as an edge.
Just as, for example, if a business decided (if it was legal) to only allow people of a certain race to enter, I would like to think that most members of that race would be disgusted enough to boycott that business and the business will rightly fail.
Finally, people already effectively pay different amounts for all sorts of things due to varying amounts of tax paid.
The private sector can't detect or profit from your tax paid so they use where you live and other signals like whether you're using an iPhone etc. as a proxy for your income/wealth.