Actually, Faith being called when she was 18 isn't necessarily canon - IIRC, it's from the non-canon book 'Go Ask Malice', whereas the show itself seems to be far more clear on the idea that Faith is a little younger than Buffy (not tons, but a little).

By the time the Cruciamentum came up for her, it was probably too late. And while Faith wasn't necessarily as resourceful as Buffy, it's clear that the Council picks vamps with easily exploitable weaknesses, like Kralik's obsession with taking his pills with water, etc. Faith isn't an idiot - if she could survive the initial onslaught, she could probably pull something similar to Buffy, though probably with less Style points. IMO.