By your own admission you've heard stories that would make you not want to work in an auto plant, you've also admitted that it's tough, tedious work.  

But it's not worth $20 per hr?  I don't get it. 

The very nature of an assembly line is so that a person doesn't need to know "everything" he needs to know "his" thing.  So experience doesn't really matter when you're installing a new bumper on a car every 1.5 minutes for at least 8 hours per day.

Hi Honey what did you do today?  

I put 350 bumpers on cars today.
70,000 bumpers in a year
1.75 million bumpers in a 25 year career. 

You can share stories about the Steamfitters Union, but that sotry is playing out across the country right now, whether or not it's a union shop. 

It might not be rocket surgery, but that's back breaking work.

If that's not worth $20 per hour what is?