Unfortunately interpretation plays a big role, and context can mean the difference. I call Eazy a man-slut, and there are contexts where that's acceptably funny and unacceptably unfunny.
With cards, they are warnings. They go away in the system as long as you don't start collecting them fast enough. You could earn a few cards each month and still never get auto-banned for it.
But yes, you are right in that the mods are biased. Part of the problem is because we're human like anybody else. We often try our best to be objective and to leave our biases out of it, but that's wholly imperfect. Mods can make good friends with some posters more than others and lose their objectivity. I carded Andy last weekend for some tirade, and he wholly deserved it, but it does make things a little weird personally -- at least momentarily.
Good mods do their best to go beyond that. But none of them are perfect.
This is where having a group of mods who chime in as a good thing. Having mods that represent different cultures, different backgrounds, etc., is helpful so that one person's "no big deal" becomes another mod's view of clear bias.
Bear with us as we are most definitely imperfect. But I can genuinely say that all the mods I know here act primarily out of wanting this to be a good site with a good environment for other posters as well as themselves. We just don't always live up to it. We don't always catch every infraction that goes on with every exchange on the site. And we don't always interpret things the same way.
But I will also say this about the mod team: they respect the different opinions of other mods and we try to resolve things with the mutual interest of what's best for the site in mind.
From an individual's perspective like yours, I'm sure you see a lot of unfairness as a result: why did this get a card but that didn't. And this is sort of why.