Earlier quoted context omitted.
> "With slaves, however, who were stakeholders in the system," "With slaves, however, who's stakes were forcibly held by others in the system," FTFY
You aren't the only person making this mistake but don't assume Roman slavery was like American chattel slavery. Roman slavery was still slavery and still had abuses but it was not "slavery till death, for all your generations". Nor were slaves mere physical labor. Slaves often ran businesses, engaged in basically white collar work, and often times were skilled craftsmen who exceeded their masters skill.
Some slaves were not mere physical labour. However, many famers and miners were still enslaved people, worked in far more brutal conditions without the hope of manumission.