Unfortunately, majority of candidates are interested in the take home challenge over doing live coding session. And we optimize for the widest reach.
In regards of the results, I can't speak for others, but I write code for 26 years. What I look for is how the candidate thinks of the problem. Here is one of my favorite exercises [0]. I would obviously love to do this live but people get super nervous and stop thinking. I then have tendency to help them too much and learn much about them.
[0] >>39263923