Probably the best landline system was/is in Germany. The ISDN was a complete digital system beginning from the 80s, having features that are not present in current mobile technologies. Calling was almost instant, probably only matched with VoLTE or SIP in local networks. Deutsche Telekom tried very hard to adapt most of the ISDN features to SIP.
Living in New York and granted a US patent...
Geographically the US is much more expansive than the EU and more robust.
I would not compare infrastructure I would compare the regulations. The telcos created the tech and most likely the laws.
Thankfully time, technology, and consolidation has now reduced that down to 2 (CDMA/LTE - Verizon, Sprint, GSM/LTE, AT&T, T-Mobile). LTE will eventually consolidate that down to 1.
Oh, and this is not a premium plan or anything. I pay 7.9EUR for unlimited calls and texts, and 1GB of data.