Hey, so there is a couple of reasons we run it for free. Firstly theres no entry barrier, young people from all backgrounds come and kids that don't have laptops we try have spares to let them use. Money we found generally complicates things (where is it going, is there transparency, some locations start wanting rent money, etc). Some people find it hard to grasp also, but free youth activities in Ireland are extremely common.
Regarding abuse, people using it as a glorified babysitting service, etc. We have a rule that if a kid is 12 or under, they must have a parent or guardian there responsible for them. As we're extremely over booked (waiting list of 200 in Dublin), we reserve spots for extremely interested kids, who keep coming back and producing things and leave other slots open. If a kid is being disruptive and won't stop, we tell the parent to calm them down (Extremely useful when working with kids that have autism as some have behavior issues that parents can address there and then)or to take them home.
To date, running it for free has worked extremely well and in every Dojo, theres been little, if no issues. People are volunteering, giving up their time for free and volunteers are normally blunt with parents if its being abused.
We try to remove as much financial dependency from CoderDojo so its easier to set up anywhere and run, individual Dojos can arrange donations or sponsor if they want. In my case, I'm looking for some assistance if people want to give it, helping me setting them up.
@thepreacher thats awesome that you're starting something! If you want a hand please drop me an email: james@coderdojo.com, theres definitely some advice on things we've learned and resources we can give you!