A computer is the hardware that's either a Windows machine or something from Apple. That's it.
I can't give away a computer with Ubuntu on it. Not that there's anything wrong with it, it's just that people don't get it. Sure lots of things run Linux but they're buying a 'thing' that just happens to have Linux under the hood, like the cell phone that was mentioned. It's not the other way around of I'll buy this small computing device with built in cellular technology and turn it into a phone using Linux.
[It's just like you don't have to understand how a car works to drive one.]
As for giving them to people with a financial need, I found it often doesn't meet their technical needs.
Applications have gotten fat plus installing a current Windows app on a Windows 98 or Ubuntu system just isn't going to work.
I've seen grade schools assigning projects that require a camcorder and something like Windows movie maker. It's not that you can't use Ubuntu but there's more "know how" with Windows among parents.
At the high school level, I've seen "here's a project, finish it in PowerPoint". They need the latest version though I don't think your typical Walmart brand computer for the masses comes with PowerPoint. And if you have Ubuntu, your typical user won't be able to figure it out.
There is nothing wrong with Ubuntu but with all this technology, many people are still computer illiterate. They want the technology but it has to be Windows and a current version at that.
That's pretty sad but without good support, an open mind and willingness to learn, they'll never figure it out on their own.