Romney's comments weren't racist, but as with pretty much everything else that comes out of his mouth, they were incredibly stupid.
Israel is much richer than Palestine for a number of reasons, none of them to do with differences in culture. For a start, Israel is one of the largest recipients of foreign aid from the US, which without a doubt contributes to GDP. Israel also continues to seize palestinian land, therefore reducing the land available for palestinians to exploit, and increasing that of the Israelis. Lets also not forget that there has been, and there continues to be, a blockade on a massive chunk of palestine that accounts for nearly half of the total palestinian population.
Israel and Palestine aren't competing equally at all, and therefore it is wrong to say that Israelis are wealthier and better off because of anything other than the fact that Israel has been significantly advantaged, and played unfairly.