Not sure about ruby, but django doesn't ship with connection pooling, so that is probably why its database performance is terrible. It could be configured to use pooling.
With such a trivial request handler like the one in benchmark, only a small percentage of the execution is actually taken up in the view, so all of the time you're seeing in the benchmark is pure overhead of the framework. A longer running view across all of these frameworks would cause things to even out a bit. All that being said, however, it's not an unfair comparison. After all, a benchmark of this nature should be a measure of overhead because that's really all there is to measure.
With such a trivial request handler like the one in benchmark, only a small percentage of the execution is actually taken up in the view, so all of the time you're seeing in the benchmark is pure overhead of the framework. A longer running view across all of these frameworks would cause things to even out a bit. All that being said, however, it's not an unfair comparison. After all, a benchmark of this nature should be a measure of overhead because that's really all there is to measure.