Another point on this issue: Between (I may not be accurate with the exact dates) about 1838 to 1848, there was a massive (a couple of million) influx of poor immigrants from Europe. Most of those settled in the north. Northern factories found that these immigrants were cheaper than slaves. You didn’t have to feed them, you didn’t have to put clothes and shoes on them, you didn’t have to have a house for them, you didn’t even have to care how healthy they were. You just paid them a paupers wage and let them fend for themselves. Northerners found that cheap immigrant labor was far cheaper than slave labor.
In the north, immigration basically was making slavery obsolete.
Since very few immigrants migrated south in such large numbers, the south did not have the luxury of that labor pool and had to still rely on slave labor to get things done.
So northerners thumbing their noses at the south for slavery, where extremely hypocritical.
Yes, and the Yankees took those same poor immigrants off the ships, put U.S. uniforms on them, and sent them on suicide charges like those at Fredericksburg. The war was a tremendous “stimulus package” for Northern industry.
My grandmother told of her grandmother's views on slavery. Great-great granny was glad they finally set their slaves free exactly for the reasons you stated. It became too much to take care of them that it was easier to pay someone to help with the farming. What many Yankees don't understand is that many slave owners got them through inheritance and they'd all been living on the same land for decades. She said her family and the slaves ate out of the same bean pot, they wore the same clothes, and worked right along side each other.