If you take a standard setup, say Ubuntu Linux, running Postgres and Ruby on Rails, the ratio of your own lines of code to all the other ones you're utilizing in the system is very small indeed. And you're free to customize all that lower-level stuff if you really need to, under very friendly terms. Unless she means that it's so easy to find and use that it's a silly question?
Software 1, Lawyers 0.
Speaking of which, wasn't YC supposed to open source some of the legal things they have?
If you take all of the case law over the last 300 years, the ratio of your contract to the existing legal infrastructure is very small indeed.
And you're free to customize all that lower-level stuff if you really need to, under very friendly terms (it only gets expensive if you have to defend it in court).
Anybody who is highly specialized, and considers themselves more of an artist than an engineer cringes when you say 'make this super generalized' Try telling a graphic designer to make a template for a few dozen random sites.
"It's like asking 'Where to find standard software and other boring technical stuff for my startup?'"