That's part of what I'm asking, if you shell out extra to buy a piece of high-quality electronics, do you need an extended warrant?
I'm pointing to this part of your OP:
couldn't she just get a cheap laptop and the extended warranty with next-day onsite service?
My answer is: get a higher quality electronics that is less likely to fail, than a lower quality one with extended warranty. Not only because you'd avoid the hassle of trying to apply the warranty (that may or may not apply for whatever fault of damage the hardware has), but also because a high-quality hardware will less likely to fail once the original ,or even the extended, warranty expires. For starters, some warranties only cover factory defects or faults that came with the product before you began using it. Bringing in a faulty or damaged laptop (where that same damage would not have happened on a higher-end machine) has a risks and expenses even if the warranty covers everything (you'd still need to bring it and back, which can be expensive in either time or gas or both, especially if the service centre or whatever is far away). Buying a higher quality hardware has somewhat less risks, because it has less failures in the first place.
I can actually cite an example: I have a cousin who brought a netbook made serviced locally (I think it was IBM's Classmate PC or something). It was one of those 100$ laptop knockoffs with the intent "For education". Aside being ugly, having an irremovable handle (at least, I don't think it could be removed without exposing electronic parts), having poor heat venting and having the smallest keyboard I have ever seen short on mobile-phone keyboards... it has a bad sound-card chip. You can HEAR the distortion. Upgrading the sound card drivers (which were hard to find, naturally) helped a little, but not much. No matter what software you ran, it worked bad.
She got it serviced on a warrantry, the guy removed CCCP on it (yes, I've installed that) and... the problem still persists somehow. This comes to no surprise as it was the cheapest laptop they could find.
Meanwhile, my old EEEPC 904HA still works like a charm. And it is several years older than the brand new
laptop. This is a laptop that has a clay jug dropped on it once, not to mention the usual bumps and bruises of my regular use.
So, yeah. Buying a higher-priced and proportionally higher-quality
laptop will likely be a better investment of your money than extended warranty.
Oh, and buying an extended warranty for already high-quality hardware? Well, because some people take greater use out of their system and a longer warranty may still be a better investment than a new laptop. Besides, it is sheer force of habit of companies. Why shouldn't
they sell extended warranties?