If I remember correctly, some major ancient Greek city-states (like Athens) used allotment to choose its politicians. Allotment, also called sortition, is when you basically choose who leads you by picking straws or winning a lottery. The reasoning that the Greeks had for it were based on several factors, like less susceptibility to corruption, but one of the major excuses of it was simply:
Running a city is not hard.
Enacting policies is not hard. You sign papers. The leader makes their decisions based on feedback from everyone else, not themselves. You use the majority opinions and/or the expert recommendations. No policy-maker is to ever make their decision based on their internal gut feelings and the overwhelming majority of them don't have a polymath background that authorizes their own knowledge.
The mayor of a city is not making their own judgements on the conditions of the roads. His or her Department of Transportation will hire experts to inspect the roads, and people with degrees in Urban Planning or whatnot will make recommendations on what the mayor finally decides to do about the city's major roads.
I bring this up as a perspective to consider, I'm not telling you the Greeks were right and allotment is better for democracy than election. But, I'm saying it's a logical argument with historical backing to have a 17-year-old as a town's mayor, because most of the major decisions that the mayor makes is still based off of external opinions.