Actually, this got progressively worse over time: older cars have really big and non-tinted rear windows, so no problem to "see through" (but I wouldn't want to

Actually, this got progressively worse over time: older cars have really big and non-tinted rear windows, so no problem to "see through" (but I wouldn't want to land on the roof after an accident with one of those). Newer cars, even non-SUVs, are already worse in this regard (smaller windows, often tinted, bigger headrests). If you add SUVs, pickups, vans etc. to the mix it gets even worse.