The logistics of supplies and rescue are a lot easier, sure, but the two environments have more in common with each other than the rest of the surface of this planet. You already need to live in artificial structures that can take a pounding, grow your own food with little from the environment but sunlight and some raw materials, and you can't survive outside for very long without ample protection. I mean, for a training environment, where else would you go?

Also, if you look at the context of the quote, you can see that they're making an analogy:

  Living there [Mars] is comparable to getting by on Antarctica, and provides 
  similar challenges. However, the South Pole now has a number of very advanced,
  large research stations that boast a great deal of modern facilities that provide 
  a good quality of life. These looked very different 50 years ago. The Mars 
  settlement will develop in the same way.