Internet is much cheaper in Europe than in most other regions and there's more of it. Europe is effectively the center of the Internet. Most of the time (in regions like Asia-Pacific and Africa) this is simply due to having more time and money to build it, but when comparing Europe to the USA, it's probably because of regulatory structure - more competition, less monopolization.
What do you mean? Is peering/transit actually more expensive in the US? Residential internet isn't really relevant here, and if it was, it would still not really make sense considering that Germany (where they have their main datacenter) has much worse internet than the US according to most speed/bandwidth averages. Because if you are not referring to residential ISP, I don't think there's any peering/transit provider monopoly in the US
Yes. I suspect that because of the low number of residential ISPs there's less internet infrastructure in general and less competition. Who needs peering if there's only Comcast? You point out that networks can exist that don't serve residential customers, but who do they serve - mostly other networks which don't exist because they can't serve residential customers. The entire US is just the access region for a few networks to backhaul to NYC, Chicago and SF, not a full fledged network itself.
