Slavery was not just a matter of conscience, it was a function of the slave power.  White people who dissented in the south were beaten and exiled, if they lived.  Add you you equate slavery with abortion when the amendment which at least attempted to give freemen rights was also used to justify legal abortion.  In both cases, it was a question of state government power imposing moral choices on others.  You are confusing moral scorn with freedom of conscience.  The moral scorn that banned abortion and sodomy also abused blacks and Latinos and imposed the Slave Power on others in the antebellum south.

Support for the poor is socially decided, as well as individual.  In a democratic country you don't get a right of conscience to avoid paying taxes for this.  Don't elevate your preference for dine and dash tax policy to a moral viewpoint.

Don't talk about slavery until you read about how the slave power worked in the South.