A more common "entry level" position to gain a foothold in politics in urban areas is usually as a prosecutor. The career path is often to then run for DA ( whatever they call it ) of a largish city.
I'd trace this back to TR, the decline of machine politics and the rise of meritocratic city governance. Indeed, Barrack Obama offends many Conservatives because his background is as a community organizer, which harkens to their ear back to machine politics.
That's a peculiarity of the US system where the prosecution is heavily politicized and judges are elected. Other Western countries don't generally have that.
I'd trace this back to TR, the decline of machine politics and the rise of meritocratic city governance. Indeed, Barrack Obama offends many Conservatives because his background is as a community organizer, which harkens to their ear back to machine politics.
Obviously, this varies.