The reason is smart people can figure out git, or databases, or objective-c, or whatever, in a fairly short amount of time.
For example, my co-founder learned objective C off free online video tutorials and built an iOS app (talking an app with serious firepower and back-end transaction logic) from start to end by himself in less than 3 weeks.
That's why we're not as concerned about what you know right now as what it's possible for you to learn in 3 more week.