Medical services are horrendously overstretched and something does need to be done about the colossal number of missed appointments. Some sort of deposit/fine system seems reasonable at first sight but can't distinguish between people who genuinely forget an appointment and are sorry for having done so and those who just can't be arsed to turn up - penalising the former group is unfair.
It doesn't help that usually appointments are months, sometimes several months or even many months away and thus are easy to forget. One of my local hospitals sends out a couple of reminders by SMS, one a few days beforehand and the other the day before, but I doubt if all hospitals and surgeries do this and it's little use to those without a phone and/or the very elderly (often one and the same) anyway.