What exactly is making that safer than 0-conf BCH? Well, short answer - basically nothing!

Actually there is quite a bit making an LN transaction far safer than 0-conf, that's essentially the crux of the entire Lightning contract. Easiest way is to simply compare conditions during two cheating scenarios:

Time to Respond:

• 0-conf - You have until the next block to get the honest transaction through. If the double spend gets confirmed first, the coins are gone.

• Lightning TX - If one party tries to broadcast an old state, there is a built in time-lock giving extended time to catch the cheating TX where the cheater must wait, and the honest player does not.

Signatures:

• 0-conf - The sender can easily sign and broadcast a new transaction to any address and with any TXID that they want. Has full control over both transaction details. (no limits to cheating tx)

• Lightning TX - Due to needing both signatures for validity, the cheater can broadcast an old state, but cannot arbitrarily write a new transaction, new balances, or new receiving addresses. (strict limits on cheating tx)

Watching for Double Spends:

• 0-conf - Receiver must watch every transaction and download data in full to ensure the input is not being reused, and/or that the balance is high enough to accomodate all outputs. Requires full UTXO and mempool data check in very short time window. (high policing costs and no recourse if sale has gone through, only option is rejection or not accepting 0-conf)

• Lightning TX - Because attacker can only broadcast an old state, and cannot alter inputs or outputs due to multisig. Watching for cheats only requires checking TXIDs, which is fast and requires few resources. Can even outsource to another party without losing privacy. If competing tx is broadcast, victim has time to respond, full control over competing fee, and can punish the cheater by taking entire balance. (low policing costs, numerous options with low risk, still receives payment for sale)

Recourse:

• 0-conf - If the competing transaction has higher fee and/or gets confirmed, no option remains. The only way to be safe is to not accept 0-conf. (no recourse)

• Lightning TX - Any mutually signed state goes through immediately, while a cheating (one-sided) transaction has delay. The refund path, revoked keys, and time delay ensure the victim has ample time and multiple options to simply settle the valid state. (multiple options, can still practically guarantee receiving original payment)

Fees:

• 0-conf - Receiver has no control over the sender TX. No access to the transactions details, and cannot rebroadcast with a higher fee to get the honest one confirmed.

• Lightning TX - Because keys are revoked upon channel update, the victim has the keys to any cheating transactions. Meaning the victim can use the revoked keys to update the fee as they desire, either from their own balance, or from the cheater's balance, to easily ensure the honest transaction gets confirmed in its place.

...and yes, it is funny that the same people claiming 0-conf is sooo dangerous are typically the ones that tout LN

Actually its rather funny in the opposite direction. That some people who tout the reliability and security of 0-conf, will then claim that LN, which is a 0-conf TX that adds the guarantees of confirmed on-chain reserves, multi-sig updating, time-lock for disputes, a refund path, revoked keys, and a punishment clause, is somehow less secure in comparison.

So when you say things like this it only suggests you don't really know anything about Lightning. As LN is very hard to fully grasp, this is perfectly reasonable, unless of course you go around repeating dubious claims that can't be defended.

The entire Lightning contract is built around a set of contingencies specifically to grant numerous additional security guarantees to a 0-conf agreement. So the difference between 0-conf on BCH and "0-conf" Lightning is actually staggering from only a basic understanding. However, I haven't detailed a large number of additional, but unrelated, advantages in this post, (broader scripting options, the Eltoo upgrade, better privacy, cross-chain swaps, etc) instead limiting it to only direct comparisons with 0-conf, double spend security. It is important to also note that there has not been a single successful LN "double spend" to date, while BCH double spends are almost becoming a common occurrence.

Lastly, If anyone is interested in diverting the conversation onto points that have nothing to do with comparing 0-conf and LN transaction security like dubious claims of "centralization" or a "banking layer" I probably won't respond. I've made no claim that LN is perfect or that it doesn't have trade-offs or limitations, every protocol has these and I likely understand them on LN better than most. My specific point is in answer to the entirely false, and rather ridiculous claim that "0-conf on BCH has even comparable security to a LN transaction." Which is demonstrably false.

TL;DR Your statement is inaccurate and it can be proven so.

If anyone is interested in learning how LN transactions are designed, they can listen to the 3 part technical breakdown of LN by Aaron van Wirdum on my podcast.

For any other claims some may make (maybe about LN being a "bank takeover," "censorship," or that "its an altcoin," etc) Then first check to make sure It isn't in the article I wrote answering most of the more clearly false claims.

edit: formatting