That's the problem with US Airspace that GA traffic can legally operate in this way without talking to ATC... They can also fly along in the airway... Without talking to ATC.
It's the same in the UK, so I wouldn't go pointing fingers at the US too quickly.
In the UK, you can take off, and legally fly IFR in "G" airspace without filing ANY flight plan, and without talking to ATC. The only reason no one appears worried about it is the amount of radar ATC has access to.