[solved] According to the school of ethical universalism,

it is up to each business to set its own standards for deciding whether the use of underage labor is ethically acceptable or not.

if the use of underage labor is acceptable in a particular culture/society/country, then it is ethical for a company to use underage labor in conducting its business activities in that culture/society/country.

if the use of underage labor is legal in a particular country, then it is ethical for a company to use underage labor in conducting its business activities in that country, no matter what the legality of using underage labor happens to be in other countries.

there are ample grounds for rejecting the principle of ethical relativism that the use of underage labor is ethically permissible in those countries, societies, and situations where the use of child labor is normal and customary (and also legal).

whether the use of underage labor is ethically acceptable or not hinges upon the ethical standards that each country government establishes for businesses located within its boundaries.