We saw the same episode and wondered exactly the same thing. Ok, so maybe they wouldn't have gotten the rooftop terrace, but all her other wants and needs could have been met for the same money in any of a dozen RVs. Oh, and it would have had heat, AC, and no composting toilet.
Ok, so it wouldn't have had the reclaimed wood on the walls and ceiling, or the tile floor and fancy sink (which I've seen at Lowe's). And yes, it would have looked like a camper rather than a house... but in my opinion, it would have been significantly more functional...