There’s a lot of things in this world that I think I have a sound understanding of that, usually after a Wikipedia binge or YouTube bender, just aren’t inline with reality. These usually aren’t fundamental things (although my recent dive into corporal discipline of children was something of an eye opener) but more and more I find myself astonished at just how wrong my intuition can be. The most recent example is the simple petrol pump and the mechanism that stops the flow when your tank is almost full.
So in my engineer brain I figured that there was some kind of sensor embedded in the end of the nozzle and, upon fuel reaching the outside of the nozzle the pump would be alerted, stopping the flow. Of course I often wondered how they managed to detect fuel on the outside of the nozzle whilst ignoring the inside but I figured that there were people much smarter than me working on that problem and it was a simple matter of engineering. Of course I was right about the latter but I never expected a fully mechanical solution to it, especially one not as elegant as they show in the video.
It really is true what they say about what happens when you assume something 😉