That very well could be the case in the U.S. I know ATC in IRL/UK don't use primary for distances greater than about 30miles, there would certainly not be overlapping coverage. Secondary provides all the info required, inc speeds altitude direction, in fact new systems are being implemented to give a readout of information that is currently only displayed in the cockpit itself.
You're right though, It is funny that the press would expect Russian bombers who are probably testing response times to their detection and interception to tell everyone they are there!!