If you don't use more than a gig or two a month, that's close to one of the cheapest plans around. There are some cheaper prepaid plans, though.
Check out this map:
https://i.redd.it/2b7uoxjoprqz.jpg
For costs to come down, you'd need people to adopt single-state or two/three state plans on the East/West coast. But starting such a network would be prohibitively expensive. For example an "only California" plan could likely be very inexpensive and comparable to Europe.
That's interesting because VoiceStream/T-Mobile used to offer that exact plan in various clumps of states. They were called "Neighborhood Plans" and varied by area. In my case, I had a three-state plan covering Texas, Arkansas, and Louisiana. $50/month, as I recall, for 3,000 minutes, 3,000 SMS, included long distance, roaming across all of those states, and some amount of data that I can't remember. The northeast had a similar one for Maine down to part of Virginia.
In the early 2000s, that was a screamingly good deal. Those plans got dumped by the mid-2000s in favor of "unlimited nationwide roaming" and "free long distance to everywhere" and now we don't even think about where our devices work and what it does or doesn't cost to call a given number (or about "calling" in general because I see so many people on cheap mobile service forums who only want a data plan and "I don't need any voice minutes"). I can now get an unlimited-everything plan that works across the entire continental US network of a major LTE carrier for $25-40/month (depending on how many people are in my virtually-constructed "Party"), so at least costs have come down from where they used to be.
However, I was wondering: How good is the LTE coverage across the U.S? Germany has really bad coverage, even along the Autobahn and train tracks with high traffic. And Germany is pretty small when compared to the U.S
It always blows my mind how that whenever you go anywhere in the world, you can get amazing mobile plans (data and call / sms) for $10-$30 dollars per month.
The US could institute a similar regime that'd permit state/local carriers to exist and compete.
$70/m for a mobile plan seems ridicilous.