I think the main reason that Apple(and a lot of other manufacturers) use these is because they simplify automated assembly. Since they're using torque wrenches to screw it in, it's better to have a screw head that won't allow the bit to fall out. Since the Torx screws can be flush with the surface they're preferable to using a hex bolt.

On another note, this is perhaps the first time ever that a DYI advocate is complaining about needing to buy a new tool. At this point, if you're a remotely serious electronics hobbyist, you should have one anyway.

EDIT: Grammar fail.

This is exactly the reason why they are used. You can set the torque on a screw gun and go to town on an automated or semi-automated assembly line.

Phillips type screws are designed to do exactly the opposite and are terrible when used in automated assembly. Phillips was invented when it was expensive to make clutch assemblies for screw guns. Instead of the screw gun slipping the screw just made the bit slip out of it.

Can't you use a torque wrench with the far more common Torx fasteners? It seems to me that they selected Torx TS fasteners for a reason, and that reason had nothing to do with automated assembly.

There isn't a post in these, though. So they're not the secure(TS) version, just a 5-point.

Aren't these actually called Security Torx heads?

A "security torx" has a small post in the center so that your torx driver requires a hollow center.

Screw head escalation and countermeasures seem to have a lot in common with DRM.

In fact, I'm going to coin the term "Physical Rights Management", or PRM :)

Apple's not the only company that uses "non-standard" screwheads to discourage opening hardware. Fewer people opening cases -> fewer warranty repairs for user error. That allows Apple to continue to be liberal with good warranty service. I'm not the only one with the experience of walking into an Apple store and getting a replacement iMac for a failing one with few questions and little hassle.

As for applecare, they seem to be pretty lenient with those policies as well. My iMac was replaced in under a year but I've also replaced an iPod after the standard 1 year by paying just for the price of applecare (after the year had already passed). In any case, I feel pretty good about not having to worry about my Apple products. I'm ok with paying for an $8 driver once in a while if I really need it to swap parts.

I do not love computers and I certainly hate the MBA (for its glossy screen). Bringing up those screws strikes me as pedantic and disingenuous, though.