An ideal interview is one where I get to learn as much about who I will be working with and what I will be doing as they will be learning about me. Generally these turn into more discussion based interviews where we talk about the issues the company is having and how I might be able to best solve them. They still get a good idea about how I think and work by discussing the problem back and forth. I also get to see how they think and work.
Frankly, I white board problems very well. But when companies ask me to do so in an interview I want to see them do it as well. I want to see their ability to code as much as they want to see mine. Same goes for a take home test. If we are going to work together and you have to see code of mine, I very much want to see yours to make sure it is up to my standards.
I just ask because it seems like trying to get work done for free through code exercises is much more trouble than it's worth.
I had a similar experience with a company in Berlin, Germany. They didn't care about the code or my skills. Only if the submitted solution worked against their existing tests.
I think it's just a sleazy way of getting things built for free. Basically, write only a test for the functionality you want. And give the actual task to job candidates. If someone succeeds, you have both the algorithm and its test for pennies. It's based on P = NP. Testing the result is easy. Designing a solution is the hard part.
I now refuse both technical interviews and take at home tests. Limits my choices a lot. But the ones that remain are usually top shelf.