You can have your parents open an account for you if you're a minor. There are quite a few requirements as well as some legal documents that are involved with opening a bank account, so it makes sense that it would be closed off to minors. Services such as loans require even more requirements and even more legal documents that it's better for minors to not look into it. It sucks that age is being used as a yardstick for mental and financial capability, but this may be the best way to kind of stop young people from entering deals and legal responsibilities they may not fully understand.

Bitcoin being decentralized means you don't need any documents nor consent from anyone, so you're free to use it. There are no money services to apply for, but you can strike up deals with other users in lieu of them, but you're going to have to take full responsibility of yourself.

In all, I think it's pretty fair. The banks have an obligation to take care of you, to some extent, since you're their client, and they're free to impose any age requirement they wish. In using Bitcoins, you're basically alone, so you don't have to conform to any policy.