Videl was literally ducking and jumping around early on. Definitely looked like a smaller, well-trained fighter handling an unskilled, muscle-bound thug.
Kid Chi-Chi was already naturally strong considering how easily she handled that T-rex . Yamcha and Puar comment that she was strong for being able to kill it despite being scared rather than the helmet itself being deadly making it clear that a normal girl her age wouldn't be able to replicate...
Maybe if he got a lil serious (Roshi's statement even implies Goku punched the air REALLY hard to produce the shockwave from his fist), which he did the moment he decided to end it. Jackie literally defeated Yamcha with zero effort.
Piccol even expected to see some of Goku's true strength...
Chi-Chi was definitely more relevant to Goku. She was at least able to surprise him with some of her attacks even forcing him into the air and still keep on fighting him mid-air. Muten Roshi even praised her level of skill. It's also possible she was holding back considering how angry she was...
Because it's more than just wind. It's a shockwave which is why the onlookers couldn't see it (Roshi himself even trouble comprehending it).
It's actually closer to Kiai since it's a shockwave created by striking the air with great force, while Jackie Chun and Daimao merely just waved their...