I may have my answer. A friend asked me if I planted in extremely wet soil. I did. It is very dry here, so I dig and amend a hole, fill it with water, insert plant into the pool and pull the dry soil around it. My friend claims our particular clay is easily amended with sand and organic matter, and even quite useful for conserving water during the inevitable stretch of 110 degree days, but it forms a milky paste in a small pool that attaches to roots and literally suffocates them. It doesn't matter how much sand or perlite is added the paste gets to the roots immediately if the plant is put in standing water.

This doesn't necessarily explain why some survived and some didn't, but it could be that some were lucky and others unlucky as I pulled the dry soil around them. I did plant seven more yesterday using barely moistened soil then watering them in lightly and all seven looked fine this morning.

I am tempted to plant a few more in the little pools to test this theory. I have more plants than I can grow. I don't know if anyone can confirm this solution, but it was telling that someone out here who's been raising a veggie garden for decades guessed exactly what I was doing wrong. I knew that wasn't the prescribed method for transplanting but it seemed to make sense out here and it sure made getting all the plants deep and level easy, which really helps in hour blazing summer.

Roots need water and oxygen to grow. Saturated soil depletes the air (oxygen) thus the roots can't function (absorb water) and the stem and leaves wilt. Provide both water and oxygen at transplanting time and the plant will grow.