The serious economic problems of slavery may have caused much of the change but the abolitionists were a visible group with which people could identify. They were also a source of arguments against slavery for anyone to hear, evaluate, and perhaps carry forward to others. Total slavery was abolished but partial slavery has grown to more than replace it. Slaves are people who work for no money and have no choice. If you can't keep all the money you earn, you're doing some work for no money.
Taxation is slavery.
Half the population was never wholly enslaved but now the whole population is half enslaved. Total slaves were owned by thousand of different masters, some cruel, some kind. Today's abolitionists are called libertarians. They are generally considered to be crazy dreamers. Taxes have always existed, they are supported in the Bible.