But let's say we allow businesses to not sell lightbulbs to White people. Hey it's their right, right? Then let's say that in practically all regions the majority of retailers would assert this right, making it pretty hard for Whites to buy lights ;). In what way is that good for society? What healthy, just society would allow that?
Libertarian ideas like this are all fatally reductive, and they fail entirely when evaluated on their effects on anyone who isn't the majority. Not everyone starts with the same advantages. Not everyone experiences the same setbacks and barriers throughout their lives. Unless we make policies to specifically correct these inequalities, we entrench them. Oh and hey look, that's exactly what we have in the US. It's not a coincidence.
We have the same law in France and the EU recently passed a similar directive.
The same with health insurance no matter what your prior situation is.
This sort of arrangement is very common for things the government thinks are 'must haves' in order to participate in society.
Your electric utility can't kick you out just because they don't like you.