Yeah I never got the super saiyan is no a joke thing that people brought up with Super with Caulifla or hell back in the original series with Goten and Trunks.
Cabba himself got Super Saiyan pretty quick so why wouldn't Caulifla who is a much better fighter and stronger then Cabba have much truble going Super Saiyan after seeing or hearing it. Both are much stronger then Goku and Vegeta when they obtained it and should have about the same or more S-Cells.
Same can be said for the Z-Kids, Gohan was strong when he was born and the unique half saiyan half earthling and by the time the Cell saga came around he still need the trigger but it was much easier for him to go Super Saiyan then compared to his dad and Vegeta who went through alot to transform.
So by the time Goten and Trunks are around, both there fathers were much stronger when they had Goten and Trucks (with Goku already being a super saiyan) thus they had more S-Cells or whatever so it was even easier for them to transform. Trunks trained with Vegeta alot and he wasen't one to really hold back so he had training so added to this it was easier for him to active Super Saiyan, Trunks then would train and fight Goten when they would play so Goten himseldf got training with a Super Saiyan along with training with Chi-chi and higher S-Cells so its easy he would transform.
Basically, it was always easier for the younger generations to achieve Super Saiyan then Goku in Vegeta, they paved the way and allowed easier transformations.
Only reason people were mad at Caulifla is because she is a girl