Bloody hell currawong, that's all pretty bleak way to look at it but I should point out that a fair bit of what you've described can either be worked through and is applicable to Aircraft now.
1. Is this not just a result of the nozzles used? Therefor just getting the right nozzles made to do the job would solve this?
2. Not sure what this means, could you explain further?
3. This can be accrued, it didn't exist before people started Spray with Ag Aircraft either presumably
4. Not Illegal, just not for the everyday person. It's called BVLOS and can be applied for with CASA, but more to the point an Operator could likely stay within LOS of these drones as they're not exactly travelling a massive distance considering their flight time
5. Drones are already being insured so sounds like this is already not really a factor
6. This is pretty ridiculous scenario*
7. Yeah, I've read about a bunch of Aircraft going way off track/disappearing/overflying destinations etc... Yeah, drones have been known to do this but then again so have Aircraft!
8. These High Spec Drones are also operating in extremely different environments, you're talking about Operators controlling them from a continent away with hundreds or thousands of miles range in a huge variety of Areas of Operation which is a vastly different scenario.
*scenario 1 - A primary school field trip arrives in the incorrect or adjacent (downwind) field. Unseen by the Pilot who is low and clearing a line of trees that they're adjacent to.
The product being applied gives those sprayed directly 20 minutes to live. I mean seriously, come on, this is just a ridiculous scenario. Possible? Yes, but no more so than say an Ag Aircraft hitting a power line and careening off into someone nearby or doing so in the act of take-off/landing.
Think you need to go do some reading before completely writing off Drone tech as it's coming whether you like it or as it appears you definitely do not.