Questions about racial discrimination

And what sort of laws are unjust...

Now if someone or some company is offering a service to the public and provides different types of service (or requires patrons to follow different rules), the only basis of discrimination being skin color, that does seem to be unjust, according to distributive justice. Similarly, it manifestly wrong for the government to distribute unequally according to race or skin color. But is it unjust for a business owner to not sell his goods or services to someone of a different color because is a bigot? Let us not use the argument of libertarians, who appeal to "property rights" and such to reject laws against such discrimination. In that case it does not seem to me that commutative justice is being violated. Now someone might say that the business owner, like the bus company, is offering a service to the public. Is there no distinction between the two? Is the business owner providing a service, or is he selling some external good?

What serves the public? Who is obligated to serve the public?

Or is the problem not of commutative justice, but of legal justice? (Surely this problem also pertains to the (natural) love of neighbor and civic friendship, but can the acts of beneficence be legislated? Can someone be required by human law to be a good Samaritan? If I cannot be compelled by human law to save the life of another when I am able, or punished for failing to do so, can I be compelled by human law to sell soap to someone else? If not soap, then, how about food?) If members of a community stop having economic transactions with one another because of racial discrimination, then the community is in danger of fragmenting. And so laws might be enacted to prohibit such discrimination, not because commutative justice is being violated, but because it is detrimental to the common good. But is legislation the best way to bring about change? If a community is not allowed to dissolve or separate, then would it not be better to work for the change of hearts, if the use of law and punishment too would also threaten social cohesiveness and the common good?