Comment by FinnLobsien

I work in the billing space at Lago, so I think I can add a bit of color (though I'm also somewhat confused).

Technically speaking, billing and payments are two separate things.

For example: OpenAI needs to calculate how much you need to pay for the tokens you consumed across all of its models. That usage aggregation, calculation and then issuing of an invoice is billing—payments is only the transfer of money.