If you are high skill enough to do a PhD in anything meaningful, why enter into an open-ended low-paid work contract with a professor with no definite end-date on when the PhD is granted? An american has even less incentive, as the reward of a work permit is not on the other side.
Only reason should be that you want to be a professor, research can be done in private companies without this license. 95% of a PhD is worth as much as 0%.
Only reason should be that you want to be a professor, research can be done in private companies without this license. 95% of a PhD is worth as much as 0%.