Not everyone can afford a computer, either. List price for the smallest APC UPS that includes software is $59.99. Which is pretty cheep. Given the other benefits of UPSs, providing some surge and brownout protection, not having one is just stupid.
General purpose distros assume that you have what, a gig or two of memory. Not everyone can afford memory, either. And there are special case systems which would never have that kind of memory. So if you have a shitty computer, you run either older versions, or specially targeted distros. And if you are building an embedded system, you make choices appropriately.
In 2009, if you choose to have a crippled system that doesn't have a UPS, then choose your filesystem carefully.