I think scammers are well aware of what authorities can do, which is why you often only hear reports about people getting scammed, but not about who the scammers are. From what I've read about WhatsApp, while they can collect timestamps and phone numbers, the messages themselves are encrypted. So, the authorities' main lead would be identifying the owner of a specific number. But scammers know this too, they use disposable SIM cards, making it almost impossible to trace them back.
They use disposable sim cards for WhatsApp so that their identity is hidden, and they mostly use Telegram as well because of the feature Telegram offers where you can hide your number from other users even if they are added as a contact. But even if the numbers are shown, as you said, the sim cards they use are disposable and they don't have a name or an identity attached to them, so the authorities can barely be able to trace them down.
Similar scams are happening in our country as well. It's a group of unknown people scamming people using online channels such as Telegram groups, etc. What they do is they lure in the victims into making cryptocurrency investments, probably telling them they are going to get huge returns on their investments. They then take them to Telegram groups where they have gathered some other victims willing and making investments which is to gain the victims' trust that they are not the only ones making such investments.
I don't know how much money they must have made so far through this, but the numbers must be very high.