It is very different, because there were no laws requiring weavers to meet exacting standards of manual skill before atetemtping to make a living as a weaver. Of course, a a pracical matter a weaver without those skills would get no employment, but that was the market at work.

London cab drivers, by contrast, had to make a significant economic investment (as well as meeting character requirements like having a clean criminal record) in order to get a cab license, a requirement imposed by the government body responsible for transit oversight (Transport for London). http://en.wikipedia.org/wiki/The_Knowledge#The_Knowledge

I find it quite reasonable that cab drivers question why standards should suddenly vary for other people such that they can offer similar service without having to meet any special requirements. This is not the same as an arbitrary monopoly grant like cab franchises in the US.