Black cabs have been protesting about, well, various things but mainly illegal touting by minicabs. Here's the BBC report on the latest protest.
Black cab drivers in general don't have much tolerance of other people protesting on the streets or causing obstructions, but I support their as much as anyone else's right to protest.
However, I'm not sure that black cab drivers have that much to complain about. Illegal touting does go on, but there is a unit with 68 cab enforcement officers dedicated to controlling it. I don't know of any other UK trade that enjoys its own dedicated police force. I wonder who pays for it? Furthermore, minicabs who fall foul of the law face losing their private hire licence. Now the cabbies complain "passengers lives are being put at risk". I wonder how many people lost their lives last year as a result of illegal touting? I would hazard a guess it's none at all, but it's certainly less than the 130-odd cyclists who are killed yearly in the UK. I don't see a dedicated police force to reduce cycling casualties, and drivers who are clearly at fault in fatal crashes all too often retain their licenses and their freedom.
I think all laws need to be enforced, but given limited resources enforcement needs to be proportional to the threat posed to society by the crime, the threat of injury or death being the most serious. So on that basis, I can't see that touting comes very high up the list of priorities.