The problem is that the technical definition of broadband would allow a 1 megabit connection over coax cable to be broadband as it is not a narrowband connection. The FFC have implemented their own definition of broadband that is not the same as the technical definition and this doesn't help with the confusion that customers face over internet speed.
I remember way back in the early 2000s UK cable company NTL had a 128 kilobit service that they were able to define as broadband because it used their coax cable even though it often delivered slower speeds that narrowband ISDN.