Small business jets are not required to have flight recorders. The argument for this is simply that they do not carry many people, so the cost-benefit analysis does not add up.
Now, following the crash of a Cessna Citation 500 that killed both pilots and all three passengers, the UK Air Accidents Investigation Branch recommends they should be fitted with recorders. It's going to be interesting to see how the Civil Aviation Authority, and the European Aviation Safety Agency, react to this. The flight that crashed was a public transport operation - the aircraft had been chartered for a trip from Biggin Hill near London to southern France.
The investigation has taken two years of rigorous work but, although the AAIB has theories to explain what happened, it will never be sure. It believes that, at one point, both engines were delivering no power, and at impact they were undergoing restart. Exactly what part the crew played is one of the big unknowns. They may have shut down one engine, but what caused the other to stop may be a mechanical anomaly that could affect other Citations.
Today's world is uncomfortable with not knowing, even if public transport aeroplanes are small. Since the existing rules were made, recording solutions have become less costly. The only debate should be about which recording options are mandated.