In what industry? That may hold for labor trades like plumbing, electrician, etc. but that data doesn't hold for teacher's unions in cities with a proportional number of private schools vs public unionized schools.
In all industries on average. Soon we'll have more data on the tech sector as more people unionize. As of right now, we can only expect the surplus to be the average surplus across industries.
Also, our work is much closer to the electrician than to the teacher. But it doesn't feel right to take this into account.
Why not? Data suggests that unionized workers earn more than their counterparts. So again An Unionized US tech worker (on average) will make more than a non-unionized US tech worker. If the former works from Bolivia an the latter works from SF it's up to them.
All evidence suggests that unionized workers earn more than non-unionized workers.
Unions are not perfect but they bring more of the value being created by employees to the employees.
An unionized US tech worker working from Bolivia will still make more than a non unionized US tech worker working in SF.