Chris Christie said it best...If you don't like the pay or the hours, then find a job that fits better. Lots of non-union workers are paid salary and expected to work beyond the 9-5 shift. When I was paid salary, some months I earned more per hour and some montths I earned less. Non-union workers that advance in life are the ones willing to put in the extra time and effort to do a good job...In a union setting, doing a good job isn't as important as seniority or tenure. And didn't that right wing kook, Bush 41 start OSHA...Do you really think OSHA is the be all, end all, of safety? Read the handbook sometime...You will scratch your head
To address some of your points and some of your misconceptions:
So in other words there are times salaried personnel are expected to work for free.

Sounds like a real bargain to me!!
Teachers are among the lowest paid and least respected degreed professionals. They are expected to work miracles with students who have parents who really don't give a damn unless they get called to school for a disciplinary problem. So why do they do it? Because they have a love, calling, or gift for teaching. Why do I know this? Because since my wife is a teacher I see it first hand.
In my place of employment (power plant) in order to advance you must pass several tests and demonstrate ability. Seniority only counts for lay-offs and vacation selection. That's all. So only the ones who put forth more effort get promoted to the next level.
No, Bush 41 did NOT "start OSHA".

The Occupational Safety and Health Administration was started when President Nixon signed the Occupational Safety and Health Act into law in 1970. And, according to Federal Law (CFR's) OSHA
is the end all and be all of Occupational Safety and Health. Please keep in mind that OSHA Regulations were written in the blood of American workers. And I should know because part of my job is being the plant Safety Coordinator. I have taken both OSHA 10 and 30 Hour courses. So yes, I have read the CFR's (Code of Federal Regulations) and don't have to scratch my head while reading them. They are not "handbooks" either. They are the law.