For what it's worth, we're helping dozens of startups hire, and I think every single one uses source control, some have failover servers, and I'd the majority have dev/staging environments (I haven't looked at their code bases, so I don't know how well documented the code is).

That said, you're right: Startups do focus more on getting things done and making sure people actually want what they're building, sometimes to the detriment of best practices.

On the other hand, startups tend to use use better (and certainly newer) tools. For instance, git vs. svn or cvs.