Because Apple said so? I simply don't have this level of trust.
Because someone disassembled their MacBook and reverse engineered things? And that person is trustworthy and competent? That is better, but even if it was true for the MacBook they reverse engineered, suppliers make tweaks to parts all the time. Can I be sure that my MacBook still has the exact same camera?
Because you opened up your MacBook to confirm? Maybe then you can trust it.
No guarantee it can't be hacked again.