Unsolved mystery

I have been pondering this question for some time: Why is it that my flower bed, completely mulched and all, has grass growing in it when my yard has bald spots?

I live in the cliff house, complete with a drop of death off my patio that ends finally with a wood fence. It's not that long a drop but the first step is a doozy. I've lived there 5 years and the run off from the house has obliterated all grass in this section with the drop of death, so now I have a nice erosion factor going on and the bottom of the drop of death is rising but the slide is growing steeper.

I was seduced by the nice weather this weekend into purchasing, loading, hauling, unloading, and dumping sod all along the drop of death. It sounds exactly like as much fun as it was. At the end, I was covered in dirt and stuck at the bottom of the hill with no equipment to climb back to the top. I had to take the long way around.

I expect a thank you note from the neighbors living in my shadow just any day now.
Also, I hate yard work. Every time I do some, I look back on my apartment days with a nice, warm glow.
And the place still looks like a neglectful home owner lives there...the bare minimum, that's my yard work contribution.

UPDATE: Now, complete with pictures and Darcy's inspection process.