Immigration is already a filter - not everyone can immigrate, and the ones that can are really motivated (since you have to jump through a lot of hoops to do so

Immigration is already a filter - not everyone can immigrate, and the ones that can are really motivated (since you have to jump through a lot of hoops to do so). So immigrants can work hard because they self-select for people who can work hard. Not everyone can - the people that can't don't end up immigrating. (I say that as a first-generation immigrant, albeit one who moved at a really young age, so I kind of straddle the line and understand both perspectives) Solutions for immigrants might not generalize to the whole population because of this filter effect.