Initially John's chances of getting a job: 1/N
Now, with the arrival of new immigrant, John's chances: 1/(N+1) i.e. he's worse off.
Sure it turned out better for the new immigrant and he can earn way more than his original country and thus this is better for humanity and the globe but it is of little relief to John who is worse off now.
My assumptions in this:
- John is a low skilled worker who will not be easily able to switch to another line of work like a software developer
- John does not have significant savings to fall back on.
Another fun fact:
- The will to let the low skilled immigrant in, in today's environment does not stem necessarily from a position of goodwill, rather it is a calculated position to keep the numbers of a voting bloc which consistently votes for a given party, constant. This can be easily explained by seeing where the opposition to limiting immigration comes from.
So keeping in mind the above 2 points, it becomes readily apparent that what politics has gotten good at is winning elections and not betterment of people. One of the parties has discovered that one of the easiest "hacks" or "optimizations" is to keep importing poor people and that way you will have a steady stream of voters, otherwise you might actually have to start improving the stock of existing population.
This is somewhat analogous to how simply being good at a written test for a position does not necessarily mean you're a good fit for that position but you've simply optimized for the selection process.
All of this to say that as far as a hypothetical John is concerned, it is of no merit to him that the world is a bit more efficient because a person from Bangladesh is able to work with a little more efficiency, indeed whatever small gains from that are outright eclipse by an increased competition in the local pool of jobs and resources.
Economists used to believe that many things were zero sum, (ie if England allows French cheese imports it will be at the expense of British cheese producers. Yet often allowing imports and increased trade leaves both France and England richer as consumers in both places value the additional selection and the competition lowers prices or foreign items can charge a premium for their novelty). Immigration is similar; it’s not zero sum.
Blaming this on a cynical political motive to create a voting block is contrary to the history of commerce and global trade and also contrary to your own analysis. It seems to me that the party most opposed to immigration is also the party that had been driving inequality by 1. Promoting globalization while also decimating the social safety net that would ease the transition, 2. Shifting to regressive taxation on sales while drastically lowering taxes on capital and its accumulation i.e. inheritance taxes. 3. Destroying any bargaining power for workers and employees and resisting minimum wage increases. I could go on and on.