How'd That Happen?

In trying to get my home computer hooked up with DSL (yes, the saga continues), it became clear that the memory on my eight-year-old laptop was insufficient. We (my friend who gets computers and I) couldn't download the software necessary for some card thing-y that's supposed to go in the side of the computer so it can do wireless. So I decided it must be time for a newer version. Get this: for $500 (one quarter of what I paid for my current laptop), I can get a new one with five times the capability of the old one. How does that happen?! Why can't they do that with cars? Or dishwashers? Or other stuff I'd love to replace?