This has been an ongoing issue. Airbnb gives guests 24 hours to pay, but this does not work with same day reservations because if guests do not pay, they never pay because the day has lapsed. There needs to be a way to adjust this timeframe for same-day reservations, such as 30 minutes or an hour. I have a strong feeling someone has mal intentions to cause me a loss because this has happened a few times already. Ever time it happens, I have to reach out to customer support to get it canceled and this takes time.
When reservations aren't confirmed, not only do hosts lose money, but so does Airbnb, so why not implement this? Airbnb should also review guest accounts that show a pattern of this.