As being a parent even if there's an option to block these charges this will cause a lot of problems. Granted it's not as bad as having surprise charges of e.g. 10K SMS @ $0.05, but none the less still annoying with impulsive buying on family/shared plans in a bad economy.
Of course they are willing to do carrier billing.. they receive a portion from each sale. I'm sure it won't be the absurd amount (30%) that other entities sacrifice but it is still there. I have blocked carrier billing on my phones due to dubious companies trying to charge to my wireless bill.