I wonder if they preferred it less if they had a way to find out how much the hospital costs before treatment.

That would make sense, at least for the people paying the costs themselves.

The economics change with insurance coverage. Once I hit my deductible, why do I care how expensive it is? At that point, might as well get my money’s worth out of my insurance company.

The last time I need non-routine care, the only thing I cared about was:

1. Is this doctor good?

2. Is this doctor/hospital in-network?

"The economics change with insurance coverage. Once I hit my deductible, why do I care how expensive it is? At that point, might as well get my money’s worth out of my insurance company"

The money doesn't come from nowhere. If everybody thinks like this, your insurance costs more money.

If you don't pay for your insurance personally, how about just straight up being paid more by your company?

Many people do think like that, and it is likely a significant contributing factor to the cost of health insurance.

I do pay for my insurance personally. Health insurance law is somewhat different than most other forms of insurance in that the premium cannot be increased no matter my frequency or magnitude of previous claims. [0]

My marginal use is a merely a rounding error in the context of my health insurer's outlays. Nothing I could do would personally affect my rate. The aggregate of many thousands of people's use determines my rate, and for that, the tragedy of the commons is fully in charge.

[0]: https://www.healthcare.gov/how-plans-set-your-premiums/