One of the biggest stumbling blocks to overcome in the name of equality is the notion of entitlement, and the fundamental question of, "How does this affect me?"
The gaining of rights inevitably means the weakening or even outright losing of rights for others. This is what makes the fight for equality so difficult; because where one party sees a quest to try and attain something that everyone else seems to be allowed to have, the other party sees an effort to take something away from them.
For an example, let's take a look at slavery in the United States. For many years, the right to purchase and own slaves was considered a normal, perfectly acceptable thing to do. Some of the greatest men in the early days - Founding Fathers included - owned slaves, and were even able to sit down at a table and write the words, "We hold these truths to be self-evident, that ALL MEN are created equal," and then go home to their slaves. Slaves just plain didn't count as men, and many didn't question it.
The prospect of emancipation was a hard and complicated one in the United States, and opinions began to differ wildly on it. Why? Because it was culturally-engrained, and because some slaveowners' entire livelihoods were at stake. To the black man yearning for freedom, Emancipation meant the chance to have the same rights as everybody else, but to the white plantation owner, it meant losing the right to have a cheap, hard-working, and reliable workforce. The black man's fight for abolition was much longer and much harder than it needed to be, because gaining the right to freedom meant the white man losing the right to own the black man.
When women gained the right to vote, it meant that every man's vote was worth half as much, because now twice as many people were voting. When women gained the right to work, men lost the right to have his wife stay at home keeping the house and cooking the meal. Women gain the right to say no to their husbands when they want sex, and men lose the right to have sex whenever they damn well please.
Every 'right' gained is a 'right' lost to someone else. This is what makes a civil rights battle so difficult: because ultimately, it relies on convincing those in power to surrender a portion of their power, when all they can see is the power they are giving up. For everyone to have a slice of the pie means less pie for those who already have theirs, and it's all too easy to fall into the trap of only seeing the pie you are losing, and not the pie that others are gaining.
Equality, at its core, means that some people have to be convinced to give up things that never should have been considered their right
in the first place.