A camera can find mistreatment before it turns critical, and then the sitter is replaced.
That is protecting the baby's health, which sometimes reaches the level of saving lives.
Your logic only works if camera footage goes unwatched until the day the babysitter exits the business.
Edit: And that 'thin line' remark is 100% a strawman. I don't know how you can admit it isn't the "intended meaning" and yet claim it's not a strawman.