Fido roam question

My parents both have Fido lines on my account and they travelled recently outside canada.

They didn’t intend to use roaming, but I guess turned on their phone and it may have connected to the network?

Either way, both lines got a $18 charge.

Why is it thaaat expensive to make a small mistake? Is there any way around it? Is there no way to turn off roaming for my slightly less technologically savvy parents?

I called Fido and ended up not being able to reach a human and just got scheduled for a call back next week. I’m thinking of moving to a different provider (maybe freedom) but want to ask what my options might be here.

I agree Fido gets to charge whatever they want but is there no recourse for an unintended mistake?