To nitpick a bit, your idea might be true, but your arguments don't necessarily hold up. Firstly, the discrimination against immigrants is mostly a social problem, not a political one. The policies in most of Europe are quite liberal, but people seem to be racists. In the US it's the other way around (at least to a certain degree). Reasons for that might be higher experience with immigration, the diversity of immigrants to the US which makes it harder for them form communities closed to the outside, and a positive feedback loop that starts with integration (giving them jobs etc.) leading to wealth and education which then leads to even more willingness to integrate immigrants. The success in the US also seems to be highly divergent for different groups, i. e. asians are much better integrated (at least economically) than blacks, even though the former immigrated more recently and therefore had less time to adjust.
Regarding social security, every EU country spends more (as % of GDP) than the US on welfare, thus making cuts more likely. If unemployment benefits are cut, the unemployed have to switch to cheaper cigarettes. In the US, they die. In numbers: the unemployed in Germany get 60% of their last income (67% with children) for up 36 months. After that, they get about 400$+rent+heating+ electricity. In the US it's 3x% for a few months, and apparently not even food stamps after that.