There’s no regulations preventing them from quoting prices to you.

There's regulations that prevent them from being undercut by entities that are willing to have transparent pricing. The problem here is not lack of regulation. It is a lack of competition. Regulation forces providers to adopt a particular business model and that model allows the kind of pricing shenanigans we see. At the end of the day everything comes down to dollars and a lack of pricing information means it is not possible to compare like services across providers. Being able to compare supposedly interchangeable goods/services is a core part of the free market and it is missing from healthcare in the US.