A surfactant "wets" the surface allowing the product to stay on the leaves long enough to be absorbed into them and systemically work down to the roots; the surfactant alone allows the first appearance of dying while the root uptake finishes the job.
The larval frogs and the juveniles were the most seriously affected probably because the surfactant causes the skin to bead water and interferes with the natural surface "breathing."
Spraying the frogs and tadpoles or the trap they are in does not truly represent field conditions as the instructions clearly suggest you spray only when rain is not forecast for 24 hours and tells you not to water after use.
Sadly, too many scientists can't leave their biases or their tongues holstered.
It is historically not beyond Monsanto to seek regulatory means to control a market. The patent on glyphostate just ran out a couple of years ago. So it is not mere tinfoil to see the possibility in NSF funding of this research as a freon redux. It's just awfully hard to tell.
My chief complaint is that a regulatory risk management architecture is opaque to political manipulation, not to mention too often destructive to its justifying precepts, favoring instead continued power and perquisites for its paper-pushing oligarchy. Needless to say, today's grant-mongering professorate is not above dependent complicity therewith, however often unconscious. It's just not a system capable of producing implicitly trust-worthy data, as you noted.