I am the exact same way, and yet I struggle to articulate this. People say to me "why would you be excited to own a carwash?" (example biz, I own none right now) and my answer is basically what you said -- its this kind of huge, real world, testing environment/challenge. How can we increase efficiency here? How would modifying the soap mixture affect the cleanliness of the cars? So many inputs and outputs to experiment with, I can't think of anything more interesting....
A company I worked for had a supplier who cut metal. The owner was hardcore about making money. They wouldn't start cutting until he was devoting 95% of the sheet metal to product, and if the machines stopped cutting for more than 1 minute, an andon light would start flashing. Needless to say, he ran a very tight ship!
I'm glad that section resonated with you! I spent several hours writing and rewriting that section, trying to articulate what exactly I found so alluring about becoming a founder.
Last year, I considered building software for sheet metal shops,[0] and people warned me that I'd get bored building software for a market I'm not passionate about. But I never felt like that would be true because whatever the business, the part that's fun to me is getting to play with all the little knobs and levers of and seeing whether my choices yielded good results.
[0] https://mtlynch.io/retrospectives/2019/12/#interviewing-mach...