just about nobody who Kickstarts a physical object has any idea just how hard manufacturing is,

Yup. I've backed a number of Kickstarters and only one has failed to deliver, but I believe only one, maybe two, of them have arrived on time. Mostly it seems that the people estimating the time it takes to manufacture forget to factor in time for getting a prototype that fails to live up to expectations and having to go back for one or more rounds of redesign.