The early Miatas had a functioning oil pressure gauge, as in my 1991.
A few years later, Miata went to a similar looking gauge, which was really just an idiot light in disguise. It was either off or on.
Why did Miata abandon a real oil pressure gauge? They were getting complaints from people who didn't understand that a cold engine has higher oil pressure than a hot engine, and assumed there was something wrong with their car when at idle with a warm engine, the oil pressure dropped. Miata had to deal with numerous warranty claims from owners.
So, idiot lights really do serve an appropriate audience.