From Cloudflare blog about why EU prices are lower (around 50% cheaper than US at least according to cloudflare)

The value of an exchange depends on the number of networks that are a part of it. The Amsterdam Internet Exchange (AMS-IX), Frankfurt Internet Exchange (DE-CIX), and the London Internet Exchange (LINX) are three of the largest exchanges in the world.

In Europe, and most other regions outside North America, these and other exchanges are generally run as non-profit collectives set up to benefit their member networks. In North America, while there are Internet exchanges, they are typically run by for-profit companies. The largest of these for-profit exchanges in North America are run by Equinix, a data center company, which uses exchanges in its facilities to increase the value of locating equipment there. Since they are run with a profit motive, pricing to join North American exchanges is typically higher than exchanges in the rest of the world.

There _are_ non-profit neutral exchanges in the US (eg https://en.wikipedia.org/wiki/Seattle_Internet_Exchange), but they're just not as dominant as they are in Europe.