My cims are 50% very educated, but I see areas with University, elementary school and high school at a walking distance, but the cims are not educated. Maybe they need time, I'll see.
Obviously. A PHD is not earned overnight.

As long as citizens have good access to education from any part of the city, they'll get their diploma eventually.
Since Campus was released, there's been a revision to the education system. Uneducated adults can't attend schools because it's outside their age group. To combat this, libraries give education to all age groups. If any citizen visits a library, there's a small chance he'll gain an education level when he leaves.