How would you actually ensure that they aren't (for example) banning customers of a protected race or other class if they refuse to provide any information on why a user was banned? All you can do is act on faith if their policies are secret and their decisions are also secret.

This is less far-fetched than you might imagine. TikTok moderators were ordered to prevent disabled users from appearing in feeds [1], which in practice is blatant discrimination against a protected class - but you'd never know about it directly since even if you figured out you were hidden from feeds, why would they answer unless they were forced to?

[1] https://www.theverge.com/2019/12/2/20991843/tiktok-bytedance...