> It would also hurt hiring and make employers more risk averse if they know they cannot get rid of poor performers easily. This impacts young inexperienced workers especially and is part of the reason places like France have youth unemployment is around 20% while US youth unemployment is around 8%

Youth that are in post-secondary education and not looking for work are included in that 20% figure you cite, and France has a much higher post-secondary education rate than its neighbors. I don't think your assessment that it's caused primarily by unionization holds up.[0]

> You're assuming that a tech union would prevent people from being laid off and maybe it would to some degree.

A primary goal of such a union would be to negotiate better separation terms in a layoff scenario, not necessarily avoid layoffs altogether. Markets are unpredictable and things happen, but people should be taken care of in the event that it does happen.