We have a very topsy-turvy education system, don't we? Because all young people go through things together there is an expectation that they all meet a minimum standard by a certain point yet people all work at individual paces and learn at different speeds. But we do not have a system in place to keep people in education (or the political will to support them) until such time as they are ready to enter society.
At the same time young people are put under a lot of stress to be at a certain point by the time they are 18 but we as adults know that if full-time education isn't for you you can pick up the slack later in life. But we don't want to tell young people this or they will immediately put their feet up and 'worry about it later'!