Also the samples are taken from the inside of bone/fossilized tissue that has undergone quite extensive cleaning prior to grinding/crushing and processing. It is possible though for contamination to occur at almost any point in the process.
The whole point of drones is that you're not putting your own soldiers at risk, so you don't care if it gets shot down. That only costs money, and the military has as much of that as it wants.
Your first sentence is somewhat valid, the second not as much. One could say it depends on the war. Most major conflicts are resolved through economic means especially being able to build things faster than the other nation-state is able to destroy them. So saying it 'only costs money' is not true. Money is the ability of the nation to build and supply itself or other nations with product or services. If the manufacturing of these drones becomes all consuming (literally for the economy) then this could result in the need to cease the conflict.
"Experience has proved that some people indeed know everything." -- Russell Baker