Used to be the answer was you could refuse to do business with any potential customer for any reason or no reason. Problem with that was some businesses decided some potential customers had skin tones or ethnic origins or religious beliefs that made them unworthy of service. At least in the U.S. we decided as a society that such discrimination was unacceptable in a business that holds itself out as being open to the public (such as the Woolworth’s lunch counter in Greensboro, NC back in the 1960’s).
There were and are some exceptions, most obviously religious organizations. There is some recognition that a Christian church that follows strict Biblical doctrine doesn’t have to conduct a same sex marriage because that is antithetical to their doctrine.
However, it gets a bit fuzzy when there is a situation such as the cake for the same sex wedding being ordered from an open to the public bakery owned and operated by person or persons whose beliefs prohibit them from voluntarily participating in or in any way supporting same sex marriage.
Many, many businesses that don’t have set pricing for set things (like your landscaping business example where you’d be quoting jobs) are able to somewhat get around this by pricing themselves out of the job. That can be a bit dicey if there’s a pattern of premium being attached to every quote for (black, white, Latino, foreign, homosexual, etc.).
Even a business such as the bakery can refuse business, but it can’t be for reasons that constitute illegal discriminatory reasons. The bakery (in the case I recall) refused service because it was a same sex couple. If they had refused service because that person hadn’t paid for a prior job, they legitimately couldn’t meet the required timeline, or some other legitimate reason that didn’t constitute illegal discrimination they would have been fine. It’s really not that hard to come up with something if you try hard enough so long as you don’t make it too obvious.
So yeah, I kind of agree a private business should be able to do business or not do business with anyone at their discretion, but like many other things, that discretion was once in place, it was abused, and it was limited.
And yes, I’m just barely old enough to remember when many buildings here, including most government buildings, had four types of bathrooms: white men, white women, black men, black women. That was two too many.
