Some people don't have the time or money to make a weekly commitment to the meetings, that doesn't mean that they're not committed to doing Slimming World and losing weight. So yes, there would be people who would veer off and rubbish SW as something that doesn't work but there'd also be people who would still stick to it without weighing in every single week and who would rave about SW.
And no, it's not the same as the gym. The gym is a monthly fee, regardless of how many times you go. The meeting fees are per meeting, it's not like I could decide to go two times a week and not pay any extra is it? No, because it depends on how many times you go.
I still haven't really got the answer of why SW say they charge the back fees, maybe they don't give a reason for it though but to be honest, doesn't really matter, I was just interested. Obviously there are lots of you who don't have a problem with them, though I've listened to what you've all said, personally I still do.