Comment by pacbard

IRB (as in Institutional Review Board) is a local (as in each research institution has one) regulatory board that ensures that any research conducted by people employed by the institution follows the federal government's common rule for human subject research. Most institutions receiving federal funding for research activities have to show that the funded work follows common rule guidelines for interaction with human subjects.

It is unlikely that a business conducting A/B testing or a parent interacting with their children are receiving federal funds to support it. Therefore, their work is not subject to IRB review.

Instead, if you are a researcher who is funded by federal funds (even if you are doing work on your own children), you have to receive IRB approval for any work involving human interaction before you start conducting it.