DWs: Prussains. KoW: Elves WM: Khador WHFB: Dwarves WH40: IG, SM
Games-workshop: changing the rules one new codex/army book at a time.
thats because jet bikes use repulsor tech to hover over the ground with no ground they crash into the hole
Except for the jetbikes that utilize anti-gravity tech. Or the jetbikes that are actually ultralight helicopters. But hey, game dynamics occasionally get weird.
Personally, I don't think Jetbikes should be affected, I think any non-vehicle that isn't slowed by difficult terrain shouldn't be affected, and for vehicles just make it skimmers ignore and non-skimmers don't.
But that's my opinion, the rules don't necessarily agree, but mainly the only difference is jetbikes are affected.