People hate immigration and immigrants as it’s seen as competing with newcomers over finite resources in a zero-sum game. This argument is flawed on many economic levels, but let’s overlook that for a moment. Let’s give everyone a stake.
Suppose that we gave every US citizen an extra passport – a blank one. Within certain common-sense restrictions (i.e., no terrorists) each person could sell their extra passport to a would-be immigrant. You could give it to someone deserving, or patriotic, or brilliant, or whoever would just pay you a lot of cash. You could perhaps exchange it for a foreign one. Likely, markets would emerge to value and trade these things, and people would pay or promise future earnings streams (personal IPOs in the best case, indentured servitude in the worst) to get into desirable countries.
But now think what would happen if a country enacted bad trade or tax policy. The sum of all of the value of the passports would equal the capitalized value of the government of the country. Poor policy that reduced this value would result in the demand, and therefore the price, of passports falling. Your passport and your extra one would probably be your most valuable possessions, worth millions of dollars. Poor government policy would lead to massive negative feedback from the citizen-shareholders.
In fact, certain un-monetizable policies would now reveal their costs, and we could see the value of pro-choice v. pro-life, certain environmental policies, etc. If your government isn’t doing things the way that you want, you can always sell your passport and get out, but likely the poor government would be ousted by citizen-shareholders first.
Finally, in the fanciful stretch case, countries that have shown themselves to be astute economic managers could engage in hostile yet peaceful takeovers of the publicly-traded passports of poorly managed countries. If each passport entitled you to one vote in a democracy, China could buy India, put it on the same economic program that has worked well for the Chinese, and perhaps even sell it off for a profit later!