Open borders and free trade share a lot of economic characteristics. Why should the US only get the benefits of foreign labor only while that labor is outside

Open borders and free trade share a lot of economic characteristics. Why should the US only get the benefits of foreign labor only while that labor is outside of the country? Crime is one reason. Immigrants from different backgrounds, countries, etc have different propensities to commit crimes. Inequality of negative effects is another reason. If we allow in unlimited hair cutters - of course the wage for hair cutters in the US may decline.