An employer is in business to earn a living, and in so doing enables his employees to earn their living. This involves putting the customer first, regardless of their personal opinions and beliefs. Before a customer's desires can be ignored, the impact on the business has to be weighed carefully. The examples you list are not out of the ordinary, and I cannot think of any employer losing business in this day and age because he hired any of them. Crossdressing on the job is not yet anywhere near being a normal situation.
Secondly, a customer does not necessarily have to be offended in order to feel uncomfortable in a given situation. Having a crossdresser unexpectedly handle his or her transaction could be a bit unnerving because it is anything but a normal everyday experience for most people. Bigotry is a pretty strong word to apply to ordinary people who suddenly have something completely out of the ordinary thrust at them. We want people to be sensitive to our needs, but I don't think we can expect that unless we are willing to be sensitive to their feelings as well.
Veronica