Ecash gives you privacy from the mint and from other lightning users because lightning payments are made by the mint and that could be anyone. The thing with kyc is that even if you use a privacy tools like ln, ecash, or mixers such that the gov't may not know exactly where the coins are, they still have a record of you buying them and not selling them. You can't really un-kyc coins, you can only obfuscate where you currently hold them.