That's what vendors will tell you but customers get visits from customs all the time. And in that unfortunate case you'll get charged with contraband plus everything they'll get on you on top of that. You probably won't have proper opsec and your house will be searched and electronics will be confiscated, plus there will be some surveillance prior to that. I'm not talking specifically about spores here, more about general onion shopping. Its easy to get in the mindset that nobody cares about a user but if you get unlucky your life will take quite a hit.