Oriental poppies .....again

I make no apology - they are simply the most stunning flowers in the garden at the moment.

I have spent most of the day gardening. I am always telling myself to do a little each day but I usually end up leaving it a week or two then having to tackle 3 ft high weeds. I have weeded, pruned, forked over, planted out and laid edging bricks around the veg plot.

Question 1: why does grass grow abundantly in the flower beds but sparsely in the lawn right next to it?
Question 2: why does grass die when Mr CG leaves a bucket on the lawn for a week but will not die when under carpet in the veg plot?
I guess we will never know.