Zero hours contracts have mainly been abused by silicon valley start ups who run operations in the UK.
Some companies like to use it was a way of getting round employment laws etc. There was a case of I think it was British Gas technicians were zero hour contractors, but under the terms were no longer allowed to use their own vans, wear their own clothes, these had to be company provided.
It was argued in court that they weren't contractors, and BG lost
Uber is another exploitation, as they employ everyone on a freelance basis, they just allow anyone to register, it has no regulation of how many drivers are operating in a certain area, as a result people who used to earn a decent living are competing against others working for Uber and then in turn start earning less than minimum wage once fuel and vehicle maintenance are taken into account.
However ZHCs (which labour renamed from casual work to make it sound worse than it is) are really useful for the bar and fast food trade. They allow for work to be at the right level of supply for the demand (like having one bar person during the quiet hours of the day) and such contracts are beneficial to students and young people who want to pick and choose when they are available to work and easily allow for them to earn extra money when they need it.