This was very common with AirBnb as well at the beginning: you could exchange private information with the host and then pay them directly. However, over time it just made more sense to use AirBnb's interface.
What these companies need to do is provide an ease-of-use, reliability, and security so that the customer is incentivized to use the official way over doing it under the table. Sure you could pay the cleaning lady directly, but having it automatically debited from your credit card is much easier.
What these companies need to do is provide an ease-of-use, reliability, and security so that the customer is incentivized to use the official way over doing it under the table. Sure you could pay the cleaning lady directly, but having it automatically debited from your credit card is much easier.