5 people dead because ---- apparently because of a loophole in the law.
Almost any kind of vehicle used to carry paying passengers operates under some kind of certification process: Buses, trains, boats, airplanes. But apparenty not submarines. Of course the owners of Titan wouldn't want to have to 'certify' it because that almost certainly would have required pressure testing the hull - probably to 150% of it's intended use pressure, and that would have been an expensive proposition - which by the way would also have certainly revealed the weakness in the design.
Hard to understand why they choose carbon fiber composite for the design of something that was going to be used in compression in the first place- maerketing? Fad engineering? Maybe to save cost handling it at the surface - (smaller cranes required etc). Carbon fiber provides no engineering advantage over steel once the vessel is in the water.