Becoming proficient in fire by friction, like most things, is a matter of practice. Once you get the hang of it, it becomes second nature. However, it's not only the understanding of how the process works mechanically, but knowing the best materials to use for the area you're in and so on. It's a chain of knowledge somewhat like the idea that one needs to know basic math to understand trigonometry.

I've become fairly proficient at using the bow drill, but I still have quite a way to go in learning the best woods to use in any given area. I could rattle off a memorized list, but the difference between knowing that list and recognizing the plants themselves is huge, especially in winter when you're most likely really going to need a fire to survive. My chain of knowledge become kinked when it comes to materials.

Above all that, depending on any number of factors such as the season, the tools I would need to make a fire kit may not be available.

Granted, I could always carry a bow drill kit with me, but at that point it's easier to carry matches, a lighter, or a fire steel. Still, it's good to have the knowledge as a backup and I practice often. I'll get back to the idea of carrying "modern" tools with you in a moment.

As Ray Mears mentioned, you can travel all around the world and find a ton of tribes that use the hand drill method before you'll run across one using the bow drill. The hand drill simpler in many ways, even though I must admit that I've never been able to get a coal using this method. I say it's simpler because you need one less skill to accomplish it versus using the bow drill, specifically the skill not needed is the making of cordage. The chain of knowledge comes into play here once more.

On a side note, the tools that you'd take with you when you are proficient in the hand drill method are smaller, lighter, and less cumbersome.

Now as Chris K mentioned, there's the case of Ishi. He had the pressure of his tribe being robbed, broken up,and hunted down going against him. Survival in such a situation is going to be tough, no doubt about it. However, a case might be able to be made, if the story related to me is true, that his tribe's knowledge and skills may not have been what they once were. When Ishi showed archeologists his superb flint knapping skills he used a stick with an iron nail driven into it as a pressure flaker. The reason I bring this up is that the iron nail represents a broken link in the chain of knowledge in some ways. Instead of having to hunt a deer for antler (or finding antlers from a dead deer in the wild) to use in the pressure flaker, he only had to get a nail, which he didn't make himself. He used a modern tool.

Don't get me wrong, Ishi was certainly amazing by the accounts I've read and I'm not trying to attack him as a person who may not have been skilled enough to survive on his own...

Just to blow my point out of the water, It could be argued that just because Ishi was an excellent flint knapper, it doesn't mean that his other primitive skills were up to snuff. He could make arrow heads, but it doesn't mean he was an excellent hunter and unparalleled fire maker. Granted, he may have been good at both, I don't know, but others in his tribe may have been responsible for different skills. Specialization has its detriments because focus on one skill may mean that a person is less versed in other areas.

To reiterate another point, when Ishi was found, he was distraught by the many losses he had suffered, was cold and hungry, and had burnt off his hair in mourning. His mental state, it could be argued, was having an adverse effect on his ability to survive as well.