I doubt you can really shoot through invisible hills or bushes.
Even with visible hillsides & trees I am often to shoot at people who are not capable of returning fire because of the high angled trajectory of the shell. At long distances the angle of incidence is greater than the angle at which the round left the barrel. So I may, for example, sit under a tree with my rounds barely clearing the branches. My enemies shells, are incoming with a steeper angle, thus hitting the impenetrable foilage.
Also when analyzing such incidents with the help of the film viewer, bear in mind that on your Front End your enemies rounds and their trajectories are not rendered to the same degree of precision like yours. They may seem to go through bushes or buildings, while on his Front End they had a fully rendered ballistic trajectory and were going above them.
Ever seen an enemy Ostwind shooting at a town or strat base? His fire seems to go right through the town, as if none of his rounds hit any building. Yet building after building blows up. Your computer just doesnt bother with that kind of detail.
Sadly, this sometimes gives people some wrong perceptions.
Also the usual lag adds to this, just like in aircombat.
