Little else frustrates and unites Perth motorists like merging — or everyone else’s perceived lack of ability to do it. Experts say it’s often down to poor driver behaviour, itself a topic that’s drawn condemnation from magistrates as recently as this week. “The thing that struck me when I came to Perth was how appalling the driving was,” magistrate Donna Webb on Thursday said. Though traffic analysts and experts say — and an online search for “why can’t drivers merge” supports — that it’s not a Perth-specific issue, drivers elsewhere have bigger pet peeves. Where a recent survey by the…