Chile’s streets are filled with protests. How did a 4 percent fare hike set off such rage?

An article recently published in the Washington Post’s Monkey Cage on the protests in Chile by Professor Alisha Holland.

https://www.washingtonpost.com/politics/2019/11/01/chiles-streets-are-fire-with-protests-how-did-percent-fare-hike-set-off-such-rage/  Chile’s streets are filled with protests. How did a 4 percent fare hike set off such rage?