Hey FD,
Interesting how these threads get off topic but make really intersting reading.
History and training in history, plays a big part in what we have today. The early years of flying and motoring were all based around mechanical devices and when Mr Bourdon invented the pressure gauge, everyone wanted one fitted to their car. Indicator lamps were just not practical as they were big, required a big battery, big switches and mostly powered by acetylene!! Tradition dictates why a lot of things happen.
If you were a struggling post war car maker then the new indicator lights were the in thing and car instrumentation took off from there. Aircraft on the other hand, had a lot of ex military jocks who needed the cockpit to look like a B17 or Lancaster and nothing elase would do so that had abig influence on how systems developed - pass the cucumber sandwiches please......
Modern aircraft systems were initially designed to meet the needs of the buyer and the purse string holders reckoned that the more gauges, the better the value for money they were getting. In reality, the less complicated systems work better and the modern electronic EFIS are just a breeze for construction, reliability and operation.
With the low oil pressure discussion that I raised, I think that you may have inadvertently answered that for me - see quote. Most vehicle oil pressure switches are set around 5 - 7 PSI falling to allow for various engine conditions so that even when the light comes on, the engine is not going to suffer much harm - (at 5 -7 psi, it is pretty well stuffed anyway!). I think that aircraft systems are set at much higher pressures for safety reasons but as always, lights tend to cause some degree of panic when they come on.
The reason that aircraft engines are certified to run without oil is so as they will not cause a fire, even if they can 'stick legs out of bed' or blow pots. Aero engines, unlike car engines, are designed to operate at high loads for long periods of time at high altitudes so it is highly desirable to avoid fires or catostrophic failures. Sudden loss of oil pressure is usually due to a major failure with oil all over the place and no gauge or light is going to help.
It might also come down to a bit of ego?? How many times have you been in a discussion and someone says "I've got the Flybit 235 with the digital cloud recogniser that answers the phone and makes coffee" but someone else has the shot blaster 2150 with more lights than you can poke a stick at!!
In the end it is up to either you or the manufacturer as to what system that you want for monitoring of your aircraft.