The problem with buying a Linux box is the cost. Discounting Chromebooks, (which have their own nasty issues with privacy), there are really no inexpensive ready to buy at Walmart priced, pre-installed Linux distro computers.
If you are willing to drop $1000+ for a pretty much mid grade computer, then you have a few choices. Otherwise, Linux distros are DIY. Which takes an effort most are unwilling to do - no matter how easy and how few clicks it takes to install.
Personally, I think all those cheap mini-PCs on Amazron should come pre-loaded with a distro. That would be the a great way for people to become familiar with Linux as a whole.