If you're employed, it's generally a lot easier to find the time to do a coding problem at home than it is to actually physically come in during a weekday and talk to people.
I talk to the applicant and try to work something out. I interview weekends and evenings if that's what they want. First interviews are always on the phone. Eventually, they have to come in, but by then, we are pretty sure it isn't a waste of time.
Especially if their day job sucks, which is one reason people look for new jobs.
Not too long ago I was at a job where management demanded 11½ days. Guess how well the team members could handle an interview at 8pm.