One needs only to head to a partying fraternity house and attempt to get in without knowing a brother to discern this little truth. The exclusive nature of the Republican Party, however, may be a bit more difficult to see. In other words, one can vote Republican, but unless you fit a very specific demographic, don't expect much in return. Fraternities, of course, have every right to be exclusive. If they don't want a lot of strangers drinking their precious Beast Ice, then that's their prerogative.
Fraternities provide benefits to the brothers.
By design, the brothers hold the privileged position. The GOP tries to do something similar. By excluding most of the population and creating benefits for a select few, they create a politically privileged position. Just take a look at Kegmeister W's tax proposal. Beats the hell out of warm Beast.