This is not true. MP 40 Volks have a shared cooldown on their smoke grenades and regular grenades, similar to Shock Troops.
Obers and Falls (and Assault Sections) do not have a shared cooldown, but they have white phosphorous instead of smoke grenades which they can't run through without slowing down and taking damage. Furthermore, instead of 15+30=45 munitions for Shocks, the WP and bundle grenade combo costs 30+35=65 munitions which is significantly more. Not really comparable.
Did you happen to forget that they have 1.5 armor, which makes them 33% more durable to small arms fire compared to any other squad?
Okay my bad. But they had this grenade. If there was a bug perhaps they should be compensated. I know they have body armor which is good. But they are a completely anti infantry cqc squad.
And please explain why airborne guards don't have separate cooldowns? 380 mp?