The basic value of conservatism is free movement of labor and capital. People are free to offer their labor to employers, employers are free to hire whom they want, consumers are free to buy what they want and sellers are free to sell what they want.
Given that why do conservatives support immigration and trade restrictions when those things are the antithesis of basic conservatives values?
Because immigration is changing the lives of Americans, that's why.
Immigrants are lowering our wages in this country, they are taking American jobs that Americans should have, they are changing us to a bilingual country because they come here without knowing the language and expect us to cater to them instead of the other way around. They are earning American dollars here and sending it back over the border to spend over there.
Wages are a supply and demand process. The lower the supply and higher the demand, prices go up. The higher the supply and lower demand, prices go down.
We can't increase our wages when we have an endless supply of workers coming into this country.