kid:
You see to be reading into what screwed has posted. Nowhere in the post was it indicated he,or she, worked full time for eight years and received no benifits. He,or she, posted that he, or she, does the SAME WORK as a full time union employee WHEN working.
As I'm sure you know, there are certain criterior required for a person to gain seniority, such as working 30 days in a 90 day period, performing new work, working during peak season, etc.
I personally know of a teacher who, during his summer vacation, worked covering vacations in a small center for many years.
I don't know screweds situation, and I don't believe you do either.