Overtaking is one of the most dangerous manoeuvres, so the rules strictly forbid it where the risk is higher: at pedestrian crossings, level crossings, in residential zones, and in the other places listed in the rules.
KET reference: KET 140: overtaking is forbidden: 140.2. at level crossings and within 100 m of them; 140.4. at pedestrian crossings; 140.8. in residential zones.