[zhdc1]

> However, there appears to be no one particular dominant one-stop type of portal offering comparisons across all kinds of product and service categories like Comparis or Idealo.

The US market is too large. Comparis works because there are only a small number of competitors in each of their targeted categories; e.g., they're able to maintain a list of current and past mortgage rates by period for almost every Swiss provider. That's much more difficult to do in the states. The same reasoning applies for mobile tariffs, personal loans, and automobiles.

Re healthcare, also remember that most people in the US have health care through their employers, so price shopping isn't necessary. When you do need to purchase private health insurance, most of the states along with the Federal government have health insurance marketplaces that provide their own price comparisons.

Also, competition among price comparison websites is much more intense, so they tend to focus on particular niches. It's easier to, say, run a successful comparison website for a single product category than for a large range of product categories and services. Compare pcpartpicker.com with toppresie.ch. They both have quality content - in fact, I would say that toppreise.ch is better, but the user interface and overall experience is much better with the former.