They don't pay you for the interview, but that usually costs the company several man-hours worth of work just for the time an applicant is on-site. Should applicants be reimbursing companies for failed interviews?
Even under the current system, at least the waste is symmetric. I give up a few hours of my time, and the company gives up a few hours of its time. There's equity. The mutual work that the company and applicant do offset each other.
A take-home test model skews that balance in favor of the company. An applicant can spend 10 or more hours working the project. The company can run it through an automated testing suite and have a recruiter spend five minutes looking it over. The system is designed to waste more of the applicant's time and less of the company's.
But it's never symmetric. Someone in HR spent time setting up the job posting and managing the process. Someone in management took the time to respond to HR and review your resum, then approve the interview. At least one person at a time is in the interview with you. Then the entire team will spend time afterward breaking it down.
A single hour spent by a bad candidate wastes at least 3 man-hours of work by the company, and most likely more.
So? Companies need employees. They have to do what it takes to get them. If it weren't worth it, they wouldn't do it.
It makes sense to me that more time in aggregate is spent by the company than the candidate, because the company has dedicated recruiting/HR/coordination people that handle the process. I, as an already full-time employed developer, don't have as much time to burn with interviewing.