It started during WW II when the US government put wage and price controls in place so that companies could not compete for employees by offering higher wages. So they competed for employees instead by offering employer-paid healthcare as a benefit. Then after the war, when the wage and price controls were repealed, the employer-paid healthcare system, instead of going away, kept getting more elaborate.
Well maybe it was once prestigious to show off your Aetna card, now its a sign of embarrassment.
I guess todays 'cool perk' is something like free lunch or allowing dogs at work. I think the "Unlimited Vacation" scam has unraveled at this point.
Another way to see it is to ask why a company should be able to reap the labour benefits of their workers and then force other people to pay for their basic needs?
No, but they should of course pay a salary that can cover all that and more. High salaries and high minimum wages is the right solution.
As with a lot of things, such as vacation time, Americans seem to prefer to provide certain social goods as employer benefits because that way it seems more like a reward for competitive merit, which one can show off as a status symbol, than like a universal social good.