At what point should a person be responsible for their own life? I wasn't taught a lot of things; I learned them with some basic googling. You can figure out how a credit card works with a few minutes of critical thinking followed by "I should look this up". Something I would expect a 30-40yo to be able to do, no?
Once you realize what is happening it can take 20 years to get out...
It is predatory. Especially to hook teenagers on them at a young age.
It would be surprising to hear that someone obtained such a high line of credit that it took 20 years to pay off, while not understanding how credit works, but I guess that is possible