> So basically they were betting on some Russian missile system that would identify war plane from commercial planes.

That's not what they were betting on at all.

They were assuming (incorrectly, as we now know) that the rebels would have smaller missiles, for example shoulder fired missiles like Stingers. Those missiles are able to shoot down planes flying at lower altitude, but they are unable to reach an aircraft at cruising altitude.

I believe the eastern Ukraine already had a closure for flights under 32,000 feet before MH 017. The military planes that were shoot down in the days before were all flying at much lower altitudes.

Surface to Air missiles that can engage planes at cruising altitude are usually only owned by state actors. They also require specially trained personal to operate them. Obviously both missiles and personal were available to whoever shot down MH 017.