Does one user-group have more leniency than another? No. As for the bits about bias...
Please understand that whilst violations of the rules have their own specified sanctions, a member's overall warning/infraction history and the severity of the given issue are both taken into consideration before anything is done.
Of course, you should all understand that much of our work is done via reports. If a number of you feel that some of your peers are getting off lightly in comparison to what may have happened to you, ask yourself if you reported them.
We, the staff, are not even remotely close to being omnipotent. We are not vigilantes whom comb threads for violations.
In most cases, it falls on the shoulders of the NB community to at least take the easy step of reporting issues you see.
Of course, I would like to also point out that the lot of you, premium or not, cannot see if another member received a warning/infraction or ended up being banned from a specific thread. The only thing that everyone can readily see are the true bans, which aren't given out lightly and typically are a result of an accumulation of infractions from different areas.