EDIT: Rather than downvoting, perhaps those who disagree with me could tell me why other companies aren't capable of "making conscious decisions about what goes in their machines"?
Apple is, after all, far from the only Unix vendor to do so. Whether it's HP-UX or Solaris, it's fairly common for Unix vendors to tightly couple their software to supported hardware. What is preventing Red Hat from offering a fully Red Hat compatible laptop that works near-perfectly out of the box?
If you do your purchase outside this list and something doesn't work, it was your decision and now your problem. It is not Redhat's or Canonical problem. They are not in hardware business, their partners are, and the information which models were tested and what was the result is publicly available.
It's tempting to compare Linux with MacOS, but also (in my opinion) unfair. Apple appears to be making conscious decisions about what goes in their machines and not simply picking the cheapest components. I think Windows is closer to a fair comparison (they have to try and support everything out there) I have had no more hassle under Linux than I've had with Windows.