If you are old enough to go to confession, you are old enough to take responsibility for meeting (or not) your obligations to Holy Church and to God.
These kids are able to get their parents to take them to school, the mall, friend's houses, sports events, concerts, etc. However, they cannot then be expected to even have them just drop them off at Church?
And you know this how? (In the case of school, though, I would suspect state compulsory education laws play a part, plus free transportation where necessary.)
I agree - old enough for confession means old enough to be responsible for their own behavior. But there is a big difference between getting oneself to Mass as a 7 yr old and, for example, resisting the temptation to steal from a classmate. One is out of their control, the other is fully within their control. Here in my area, parents rush to take their little 'stars' to sporting events, some of the kids are unwilling to go. Many do not always take their kids to school, the parents actually go to work before the kids bus picks them up (a neighborhood parent or grandparent keeps an eye on them). Many of the kids walk the 3 blocks to the boys & girls club for afterschool programs until someone in mom & dads carpool picks them up. For kids in very rural areas like ours, getting themselves to Mass is quite difficult. Mom & Dad sleep in or work on Sundays and even when asked by their child, will just as likely not bother. For an action to be a sin, one has to have some control over it. Sin = doing (or failing to do) something one knows is wrong, sinful on purpose. Kids who ask parents, relatives, and are denied can't be culpable. That behavior is not in their control.