This might be something that UK/EU folks might not be able to empathise with, but for US workers, the need for health insurance is a crucial factor in how they choose to stay/leave/accept any job.
To say folks should just "up and leave" if they feel they're under appreciated is not so clear-cut when your medications, nay your family/spouse/child's health is on-the-line while you try to run off in search of "greener pastures".
In my mind, one very real reason healthcare reform has failed in the US is that companies[1] are very aware that being the main/sole provider of their workforce's healthcare provides very strong leverage over them.
Now having said that, it is true that healthcare costs companies alot of money, and it may be something that a large percentage of them would like to avoid -- a possible factor in their preferrence for a younger workforce perhaps -- but to ignore healthcare and its effects psycologically on our society and workforce as a whole is doing us a disservice.
[1] I guess I'm really thinking of "big" companies with a need for a large dependable workforce, not your mum & pop/start-up/entrepreneurial kind...