yes, all people are equal under the *law*. people are not equal in every sense of the word.
plus, your example of women and blacks being denied jobs doesnt fit into this equation, because women and blacks were more than willing to conform to the rules set by their employer and not ask for special exemptions, like transexuals will.
what about the businesses that are owned by religious people who see transexualism being incompatible with their beliefs? should they be forced by the state to do it anyways, even if it is in direct conflict with their religion? what about the women who do not want to share the bathroom with men? should they be told by the state to fuck off?
i dont think so.