Everything is legal until the appropriate laws that make it illegal are established. Since the law decides what is and isn't legal, if there are no laws that say BTC can not function without proper regulations it remains legal. You are right thinking that BTC isn't a bank account nor stocks and since your wallet isn't assigned to your name you don't have to inform the government.
I hope that answers your question in full
see a situation where there is no prohibition on the ownership of bitcoin, so long as that bitcoin is legitimate or legal, perhaps the problem is the use in each country which has no clear rules, but buying and selling of bitcoin remains an activity that is not prohibited.I hope that answers your question in full