oil pressure gauge

For many years I have always wondered why BMW never had an oil pressure gauge on most of their models. Is there any one answer for this? If anyone has an answer, please let me know. Thank you.

1. There is no need for the driver to know this.
2. There's a warning light on the instrument cluster that will light up if the pressure drops too low. It comes on when you're starting the engine and stops after ignition has taken place (in a normal vehicle).
3. They should have had a voltmeter instead. Far more useful.
4. Hey, I think i remember they do, through the OBC.

Also gauge only lets you know about SUDDEN oil pressure loss if you are checking it at the time. A LIGHT gets attention because of it's very nature. Also people tend to 'check the dash' only when they are stationary - oil pressure at it's lowest.