An interesting blog article by Guardian Enzo, a known review and blogger in the fansub community
http://www.lostinanime.com/2012/08/are-guys-treated-badly-in-anime-and-if.html
Ya all of them are Betas. One of the reasons that I like Tenchi so much is that he evolves to become an Alpha over time, I don't see that very much in anime now days.