because bitcoin is pseudoanonym and it's volatile nature so in some country their goverment wouldn't accepted bitcoin, since they're worried if bitcoin will adopted and peple do money laundry or negative things like gun or drugs trading, in fact not only with bitcoin people do that even with their own currency same thing could happen
Cash is more anonymous than bitcoin. Bitcoin is more traceable than cash. If you are paid salary with bitcoin, then every bitcoin you spend will be traceable by the government. The source of your payment is your employer and the government can find all your spending and verify with the retailers. If you spend the bitcoin on illegal activities, the government will know very soon.