They are still going on Lightning, not Nostr (we all have LNURLS). Many big channels do routing for free, I understand why exchanges do it, some other routers offer free routing, but charged a one time fee for opening channels. So much of what's going on here is Wallet of Satoshi to Wallet of Satoshi... if they are smart, that's just numbers on a database and not really a real Lightning payment, but idunno. Alot of it is free anyway even a custodial Bluewallet (which they are phasing out) to a Wallet of Satoshi.
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Add to that that a lot of nodes try to connect to biggest and most popular nodes, including exchanges and wallets, in hopes of getting the best chance to earn sats from routing their customers' money, and using them to more easily rebalancing channels. So a lot of those who are zapping end up being zero or one hop from Wallet of Satoshi and others as well.