Because this game is supposed to be a simulation, & in reality cars do not turn invisible & start driving through one another! I love watching replays of online races as much as I like participating in them, so seeing cars ghosting ruins the immersion for me.
Ok, well, in real life...your car doesn't stall for five seconds after putting two wheels over an inner kerb, either. That's why you race without the penalty system, which sucks just as bad as a crap driver on the track. You're going to get hit either way, if you ditch ghosting from penalties (which should be the case). The best way is to race with penalties off. Then the driver who got hit doesn't get a penalty either because of the screwed up system and you can watch the replay, award penalties for the next race or kick them from the room if it is just a nightly fun race and the shoddy player is gone. Simple. We never race with penalty systems and if you look at the online racing section, that is the overwhelming case. Penalties are unrealistic anyways, so why keep them? You're going on about a simulation, but there is no charlie whiting or the fia or anyone to give a somewhat realistic penalty to. And the day they introduced drive-thrus for online penalties is the day people stop playing with penalties set to on, so that isn't happening either.
Millions of people bought GT6. Most have played some game online at some point. A lot of people take things seriously online, but most don't. It is not worth it in GT6. Too many people who have played COD and such that approach it as just a video game will drive you crazy. PD is not and can't simply cater to us who want a full IRL experience.
I don't go into rooms with penalties, because the systems suck and people ghost pass on purpose. The people I normally race with are great drivers and understand racing, so we don't have to put the penalty system on. They're also honest dudes for what I take them as and we don't have issues with cutting corners to the point that it is decreasing lap times. The only track that comes into play is the Redbull Ring and we basically have a gentlemens agreement that swinging wide through 9 and 10 is ok, because it happens and we can't enforce it during nightly races. Same at silverstone. There are a few places that running wide would normally be a penalty and end up decreasing lap times, but it would be annoying and a pain to enforce for a fun race.
No penalties = no ghost and no ghost passes. Penalties = you're going to get hit anyways or get passed. One or the other.
This is not something I would focus on when it comes to realism in GT6 lolol