I don’t know what to tell you, I’d literally never heard of," blocking the box," until you said it. Meanwhile, Gridlock is so ubiquitous and well understood that, as your quote points out, it’s a universal metaphor for a blockage or impass.

Also, if we just accept this vague use of gridlock, (I’ve never heard anyone is it for anything other than actual gridlock, but whatever) you realize that this quote explicitly states that some people use, “gridlock,” and, “traffic congestion,” interchangeably, meaning your claim thar, “gridlock,” means “stop and go traffic,” not, “contested traffic,” is flat out wrong, right?