Why do we need to make it easy for people to come take our jobs? Why would we do that?

Who's "us"? I don't know you, and I have friends who aren't Americans who have been prevented by immigration policy from taking jobs here that I know they'd have been great at. Why should I care more about you keeping your job--just because we were born in the same politically defined geographic area?

But if you need a self-interested explanation: because you don't want to be competing with people who have artificially-restricted bargaining power and so have to take lower wages. The H1B program as-is, like the old bracero program for farmworkers, is a "compromise" that benefits corporations at the expense of both native-born U.S. citizens and immigrants.

Why should you care? Possibly because you realize that undercutting your countrymen, the people you have to live with now regardless of whether they are employed or not, is something that makes your actual community now a worse place.

Call it self interest, but I want to live in a society that is functional and with neighbors that are happy. The alternative is to retreat further and further into an affluent bubble. Then, I admit, you don't have to care.

As soon as someone immigrates and becomes a citizen they are also your fellow countrymen.

Where the next huge industry starts, wherever that happens to be, will define the next super power. Having the US be attractive for foreigners to immigrate to and become citizens raises the odds the US will be that place. I don't want access to the Chinese or Indian stock markets, I want the best of their citizens to want to immigrate to the US and start companies here because the US is the best place for company formation (not arguing either way atm, just saying what I want). This type of environment raises all boats.

Instead we teach other countries best, send them home, and yield few of the benefits as they go on to start companies.

By that argument, it seems like you would be in favor of being extremely selective about who becomes your next fellow countryman. If he turns out to be a liability, you're just that little bit further away from being the next superpower. He may well not, but what if he does?

Could there be social welfare costs? Rising income inequality? Unemployment of current citizens?

If you want to frame the problem in economic terms, a frank discussion of the risks is mandatory. Right now we usually talk about it like a ca. 2008 banker might have talked about naked credit default swaps. Sure, there might be a risk. But think of how much money we can make!

"Community" is loose term - choosing to limit the boundaries to "your country" is arbitrary. There is an argument to be made that having the people best suited for a job work on it will improve long term economic viability of the product itself and in turn availability of the product to the "community". There is also the risk of losing the best talent to an entity outside this arbitrary definition of community and then get crushed by a superior, competing product/service - where is the economic sense in that?

Borders are another way of saying "local control". If, all things being equal, you would rather that political decisions happen closer to you than further away, then you are in favor of (arbitrary) borders.

I think it's an error to view concepts such as "community" and "your country" as quaint abstractions while putting full faith in "the product" and "economic viability". Economic arguments are important, but not comprehensive to the human experience. All things being equal, I'd rather live in a decent place with a decent economy, than a terrible place with great economy, or the reverse.

So I am skeptical of arguments that demand economic optimality over all other competing concerns such as culture, "community", happiness, etc. Perhaps economic optimality has diminishing marginal returns?

Economic optimality, in this case, is merely one of any number of quantifiable measures you can use to define what is decent vs terrible. How does the place of birth of people working jobs (that they are good at) change what you call decent or terrible - what is your measure?

Because if you don't let them come in and compete fairly, your employer is going to bring them anyways, at half of your salary, and let you go with a kick in the ass.

Those are not your jobs, those are jobs for the take. If you don't like the situation maybe you should consider aligning your interest with the people that is in the same boat with you, not necessarily with the ones who happen to share your nationality.

I suppose the logic is that with the same bargaining power as domestic workers, there would be a lot less exploitation. By extension, "job taking" by underpaid foreigners would decrease but competition for jobs would increase.

Exactly. I have worked with many new/aspiring Americans and have no problem with them and welcome the competition. The problem is that they have much more to lose, so they are open to abuse. If I don't like a job, I can quit, but they can be deported. Current immigration policy treats foreign workers like crap and nobody should have to compete with another worker with the same skills but with a government stamp that allows them to be treated like garbage.

Who is _us_? As soon as someone immigrates here and becomes a citizen they are us. Way more dangerous than losing your job today is losing the next silicon valley because we refuse to let people who want to come here, work, and become citizens actually come here, work and become citizens.

Competition? Nobody has a indestructible right to their job.

Somehow you never see large employers say, "You know, the real problem is, our business is just not subject to enough competition."