This is gud. But I don't think the way the lighting network works in other non custodian wallets will be the same way Binance will also use it.
I think de only similarities be say you fit generate invoices wen using either of dem and send BTC from CEX 2 CEX, CEX to non-custodial wallets and vice versa. But LN for non-custodial wallet get im own added benefit or advantage and Charles-Tim don already explain am.
Binance is a centralized exchange platform which is mainly for business and profit making. So that free transaction that happens in other wallets might not happen in Binance because they need profit in dealings.
Any person wey dey run any business na to maximize profits and Binance is no different. De free transaction fee no dey available for Binance and oda CEXs
One thing I always afraid of using Binance to send coin is the transaction fee. Their transaction fee na to kill person oboy. But e fit bi sae LN can reduce it.
In terms of transaction fees, I feel say Binance dey try wen compared to oda exchanges. I neva compare de transaction fee with oda exchanges but 0.000002 BTC no bad.