It actually has been a law in the US for quite a long time, to have cable ends on a new bicycle (but the requirements for a used bicycle are much, MUCH more lax): http://www.gpo.gov/fdsys/pkg/CFR-201...-sec1512-4.xml

Enforcement would be along the lines of, if someone is caught selling new bicycles without them, the CPSC would force a recall for them to be installed.

Not sure what the applicable UK or EC law would be.