Companies don't care about "effectiveness". They care about the share price. If sharing customer defects makes the share price go up, they'll do it. If they find out it risks the share price, they'll clamp down on it.

Tesla insisting on unrecorded verbal communication for specific circumstances is not uncommon at all. Often it's at the direct instruction of their legal counsel. You're just not aware of it, because it's secret (and protected by NDAs and an army of lawyers), so you don't hear about it, and thus assume it's uncommon.

Corporate unethical bullshit is an iceberg. You will never see the vast majority of it.