If someone is open for business and someone walks into that business seeking that service, as advertised, the business has an obligation to provide the product.
When a business is a personal service, the business should have far more latitude in which kinds of people they will provide that personal service to. Baked goods is a product and a bakery obligated to sell baked goods to anyone who walks through the door who wants to buy. Baking a wedding cake, having it constructed on site, is a personal service. Photography is a personal service, psychological counseling is a personal service, massage therapy is a personal service, painting portraits is a personal service. When it comes to a service that requires the provider to actually attend and participate in the client's activities, it enters into an entirely new category and should be entirely under the control of the provider.
When a business is a personal service, the business should have far more latitude in which kinds of people they will provide that personal service to. Baked goods is a product and a bakery obligated to sell baked goods to anyone who walks through the door who wants to buy. Baking a wedding cake, having it constructed on site, is a personal service. Photography is a personal service, psychological counseling is a personal service, massage therapy is a personal service, painting portraits is a personal service. When it comes to a service that requires the provider to actually attend and participate in the client's activities, it enters into an entirely new category and should be entirely under the control of the provider.