You actually believe that the contemporary industrial order can be maintained without force? The current order of things is massively contigent on vast amounts of potential and actual force, both intra-nationally and internationally. The deployment of police against striking workers or anarchist activists, or the military against countries that threaten to disrupt the order ... these are as much a part of "the system" as the psychological manipulation of desire to maintain consumption.

Slavery was very efficient. Slaves were fed and sheltered at low cost and produced outsize yields and profits. It was a heinous, evil, but efficient system. The Civil War was fought precisely because slavery was so profitable.

It's efficient for the slave owners, but not for the economy as a whole, as the slaves are unable to build up human capital and shift into more productive work.

Slavery continues to be very efficient, especially with mechanization. It's just moved out of the US. Eg. shrimp farming

"Well, I guess child labor did in the short term sense."

It's still working, in the global south, to make products shipped and sold all around the global north... but those of us in the north just don't see it; we no longer see children shuffling off to work, because, thanks to Capitalism's profit-over-people ideals, the labor force that has "disgusted" the consumers in the north (child labor) (and therefore properly threatened the profit of those companies using child labor) has been moved to the south... and those consumers in the north don't really "care" that a bunch of brown and asian children are doing the work now.

Yes, it is a problem, however it's not completely being ignored. For example, Canada successfully pushed for provisions to the CPTPP to push Vietnam to ban child labor.

Whatever we are doing now actually works the least, given the existential threat of climate change (Anthropocene).

It is indeed efficient—all too efficient.