Military testing is typically done by putting a few pieces of tested equipment in the field. Russia is doing exactly that in Syria with their new Su-57. Pretty sure it's where a few other of the planes got a first taste of live combat, that's part of testing. I'm sure it'll either cause some unintended fatalities.

And, medicine takes tens of thousands of lives unintentionally, if I recall correctly.

So, by this logic, AZ is now a war zone?

Medicinal testing kills tens of thousands?

Not at all. You had mentioned military testing, which is safe in early stages, and I addressed that first: the testing process does follow through into live environments. Where things can go wrong.

But no, medical testing doesn't kill tens of thousands, practiced medicine does. I may have read your post wrong an figured you meant medicine in practice separately from military testing. There's research to suggest mistakes are the third leading cause of death in the US [1]. My point wasn't so much that killing random bystanders is okay, but that there's a level of unintended death in both, and not just in testing. Society decides what's acceptable, and if for miles driven the number of deaths that self driving vehicles cause is lower than the number of deaths caused by human drivers per miles driven, well... I'd say that's a fair way to look at it.

1. http://www.bmj.com/content/353/bmj.i2139

Okay, that does sound far more reasonable than comparing dead people to a part of a recipe.