De Beauvoir Cycle Gang Strikes Again

Oliver, you're being pedantic.

No, I'm not. I'm being precise. :)

Language forms and evolves through common acceptance and usage. The common usage of "traffic" means motor traffic, and people, horses, bicycles etc are not considered to be traffic. Nobody says "motor traffic" in real life,

You're wrong on that, Niall, and usage itself contradicts you. People say 'motor traffic' or 'pedestrian traffic' or 'cycle traffic' all the time. Just Google the phrases and you'll get thousands of hits--1,730,000 today for 'pedestrian traffic'. Of course I know that people mostly use the lazy shorthand, but this serves to obscure the actual meaning of 'traffic'. Collins definition: 'the movement of vehicles, people, etc. in a partciular place or for a particular purpose'.

and attempting to redefine language like this is the equivalent of insisting that "gay" may only mean "happy".
Nonsense. The definitions of the term 'traffic' are quite clear. Also, it is of course possible to shape language deliberately rather than to leave it to pure accident.