“The pool should be empty, pristine, and easy to view.”
Yes. It’s a POOL, not a lake or some other murky body of water.
And don’t they have any life guards?
And, what about the 9 year old? What relationship if any did he have to this woman?
Was she there all alone?
Rule #1 - never swim alone.
(The answers to your questions are all in the article and video)
The pool was not CLEAR. The INSPECTOR even reported it was CLOUDY. You couldn't see the drain at the deep end.
They have several life guards, including one at the end of the SLIDE who is supposed to ensure that those who go DOWN, actually come back UP. The 9 year old boy even told the lifeguard the woman who crashed into him on the way down the slide, hadn't come back up. The guard said he would search for her. (but apparently didn't)
The 9 year old had no relationship to Mrs. Joseph. She just crashed into him on the way down the slide.
There were hundreds of other people, including several life guards, at the pool. There were several friends of Mrs. Joseph at the pool as well, and they waited for her until the pool closed. I hardly consider that to be 'alone'.