I've been on both ends of this and it takes a wasp like a whole minute of retreating and shooting to kill a gren squad for some reason.
I imagine thats to stop it chasing squads down early game and getting too easy wipes, they kinda learnt that from the Kv8 early days.
Wasp is supposed to be brits early game garrison counter, not equivalent of soviet clown car.
If you really hate fighting wasp, you can use encirclement doctrine simply for 10 muni sprint, use it to easily get grens in faust range. Then later combined with some shrek storms you can do the same vs larger light vehicles, pretty nice against USA, very difficult for the enemy to plan for sprinting axis AT squads.
Also I use the +7% range buff for Fauts which really helps vs light vehicles early.