My oppinion is, that unions in general are important since they are the best means to secure the interests of employees against corporative management.
Usually it is in the interest of a union not to ruin the business where the union members are employed. This requires a certain willingness to get along with international competition (among unions).
In a globalized world unions are only strong if they can maintain international standards. Otherwise corporations can easily out source labor to regions with weaker union standards.
So sometimes unions need to lower their standards to be competitive.
Currently foreign car manufacturers in the US have temporary advantages over domestic car manufacturers that cannot be denied.
For example they do not have such a huge retiree fraction yet.
Now I read arguments, that these manufacturers had the general advantage of being basically state subsidized in their home countries.
E.g. the german car makers in the form of a national health care system and a national retirement system.
The question here is, if this is really a subsidization.
The money for the german national health care system and the national retirement system is not made from thin air.
Both employee and employer have to pay a certain percentage based on the employees wage.
So the claim of hidden subsidization is just window-dressing.
Multinational corporations like VW have to adapt to different domestic regulations in different countries. And they will use advantages if there are any. Production in the USA allows to a certain extent for delaying costs such as retirement programs until employees actually reached the age to be retired. This is the actual problem. These costs start to kick in one or two generations later. In the meantime this system allows for especially cheap products. But that is sort of borrowed wealth that has to be paid back one day. The domestic car makers are in the unpleasent situation of being several generations further down the road and therefore not very competitive now. Maybe changing the system helps?
"And the trade difference means it costs more to buy a US car in Germany than a german car in the US."
This is not totally wrong but delusive. Because almost every car is far more expensive in Germany compared to prizes in the USA. A US made car is still cheaper than a size-wise comparable VW, BMW, Audi, Mercedes in Germany, the assumed market advantage is not existent.
on a side note
Patriotism is a good thing when it does not become blind nationalism. Reading some of the comments imparts the impression that domestic problems are blamed on foreign countries.