What are the sources of income for free services?

Question

Startups

How do they live and where do they earn from such open-to-use services such as
Bla Bla Car
or
Booking
Or any other services that are free and do not charge commission.

Answer 1

www.booking.com/content/terms.ru.html?label=gen173...
4. Free Services
Our Service is free of charge to you because, unlike many other companies, we do not charge you for our Service and do not add additional fees (for making a booking) to the cost.
Suppliers pay a commission (a small percentage of the cost of a product (e.g. room)) to Booking.com after a user has used a product or service provided by a Supplier or a guest has stayed at a property (and paid for the stay).

Answer 2

Bla Bla Car
1) investment
2) in some countries, passengers pay for travel, the company takes a commission
Booking
1) investment
2) % of the order paid by the hotel

Answer 3

Booking percentage, but blabla as far as I know is no longer a free service. It was free for promotion.

Answer 4

You need to understand that there are no free services, an exception, only Open source solutions can, and even then, regarding whom to consider it. Even the newspaper Metro, which you can get for free in the morning on the subway, cost someone money. There are many business models where the client, as it were, does not pay money.
It's just that these are completely different views, literally - mirror opposite.