It's expensive for the company too. All of the people involved in the interview process are still getting paid while they are interviewing the candidates. They aren't working on their projects that they have to complete. The company probably has a recruiting or talent acquisition team and the people on that team don't work for free. The company might also work with outside agencies or external recruiters. If you hire one a candidate from one of these sources, you have to pay them too.
It's really expensive in terms of time and money to hire people. It's really hard to build a great team.