> No. Whatever the unknown unknowns are, they're not going to be that hard to work around. Please try some humility, for real. This isn't some guy's backyard t

> No. Whatever the unknown unknowns are, they're not going to be that hard to work around. Please try some humility, for real. This isn't some guy's backyard train model project. This is a 24/7-running subway in one of the busiest cities in the world. Errors that result in shutdowns can cost tens to hundreds of millions of dollars in economical damage. Accidents can take hundreds to thousands of lives. This attitude you have is the attitude of every single commenter who asks why Dropbox has "so many employees" when they "could build it in a weekend". It shows a huge amount of disrespect for complexity you aren't aware of; and by extension, things you're not aware of in general. It's the same attitude you find in project managers who don't understand XKCD1425 and "just want it done now it can't be that hard". The attitude of anti-vaxxers who dismiss expert opinions to rely on their gut feelings. I don't know why it's so expensive, I haven't seen the breakdown, but my default reaction will be to dig further, rather than to dismiss people who have worked on subway systems infinitely more than me and casually throw in a "Nah, it's just keeping track of some train cars, nbd".