Rule reminder
In spoken Italian, 'uno' + verb is used like 'one' in English — it refers to people in general including the speaker: 'Uno non sa mai' (one never knows). 'La gente' + verb (always 3rd person singular!) describes what 'people' generally do or think: 'La gente pensa che...' Both are more informal than 'si impersonale'. Key: 'la gente' ALWAYS takes singular verb even though it refers to multiple people. 'Uno' takes 3rd person singular verbs. In colloquial Italian, 'la gente' is often pejorative or dismissive.
In questa città _____ a lamentarsi del traffico ma nessuno cambia le proprie abitudini di guida.