Good question! Violin, viola, and cello are all tuned in fifths so that means somebody (several hundred years ago) decided the string length of the double bass either made the reach too large, or the top string too thin, or whatever, and they went to fourths.
Double bass string length is generally somewhere between 42-44 and cello is around 27.5. So one would think that a short scale electric bass at around 30 could be played in fifths with a bit of effort... Mandolin is fifths and roughly the same scale as violin but with frets.
I had heard a rumor that Jack Bruce used to do this. I know he was a cello player so it could have happened, but I'm not sure.
And Allan Holdsworth, who also played violin, used a fifths tuning occasionally while playing the SynthAxe. Some songs switched tunings mid-song. He also had a couple guitars strung that way. Yeah, crazy.
Jimmy J