I don't want to answer the for general but thought I would say that I used to work at VP in those kiosks and it is hard work, the staff have to do a lot of prep before the game and are there 3 hours before kick off, the wage is pretty poor and it used to be (might not be anymore) paid per match you work and works out at being a pretty poor wage. However the majority of staff there are from agencies and will be different people every week and this means that they do not know the job and what to do. I agree sometimes the service is slow but as I have worked there I know how hard it can be and how bad the people at the games can treat you.
However I think it would be beneficial for the club to employ more permanent staff and less agency staff, maybe appeal to kids at school who need to earn some money like me and 6 of my friends did when we worked there as opposed to taking the easy option and employing agency staff who can find it hard to quickly pick up the job needed.