They say at the beginning that Goku is so detached, and what apparently seems Vegita’s apathy is similar in nature; it is our values that bind us to limitation, once freed from them our fears and desires no longer make decisions for us, we are no longer slave to them and we are unconstrained.
Apathy is different to detachment, an apathetic person will still be driven by desires and fears, they just hold no concern for others, true detachment is not about holding no concern for others but about accepting they will come and go and when they do you can invest in them only to fall as they do or you can release all commitment when appropriate.
The underlying theme of enlightenment is to embrace your nature, be true to your sense of justice, yet not allow attachments to form chains to drag you about contrary to that sense.
