Such should be left up to each state or municipality--never the federal government--but I support business owners needing a license to conduct business within a state or municipality because some standards are appropriate to require in the interest of the general welfare.
You want a plumber to be licensed because it could be dangerous to the customer and even his neighbors if the plumber is not qualified to do plumbing. Any establishment offering food products or other sustances that could be harmful to people without the people having any way to know of the danger should be regulated.
However if a state or municipality does not wish to exercise such protections for the public, that should be their right to decide too.
I draw the line at any place of business being ordered what products they MUST carry or what services they MUST provide.
State licenses aren't required to produce the results you desire. Private certifications are just as effective.
Are they? And who assures us that those who provide the certification are competent to provide it?
For me, it's a trade off. Within the concept of social contract, a business license to do business is in the best interst of all as it does give us a reasonable expectation that the business owner will provide safe products and services as advertised and, if he is not competent to do so, he will lose his license and the risk is removed from the public. It isn't much different than social contract that establishes certain laws to enforce the mutual concepts of right and wrong, insists that certain fire safety be employed, that personal conduct cannot unreasonably put our neighbor at risk, etc.
And for practical reasons, the business license also informs the local and state government who owes taxes and fees as the business owner's proper share of costs for government services.
At the same time, those who do not wish to participate in the social contract can choose to live in unincorporated areas and sell right off the farm or whatever. Of course the federal government and some state governments now also strictly regulates that. (We once bought farm fresh eggs, milk, cream, veggies, pecans, apples, peaches etc. from neighboring farms. It is much more difficult to do that now.) But theoretically, when there was much less regulation, those farmers could discriminate against anybody with impunity.