That's incorrect, holding a B1/B2 US visa only allows you to arrive at the port of entry, the actual permission to enter the country is always left to the border officer interviewing you
It is legal to show up at a port of entry without any sort of anything. If all it allows you to do is show up at the port of entry it's a worthless scrap of paper.
It is legal to show up at a port of entry without any sort of anything. If all it allows you to do is show up at the port of entry it's a worthless scrap of paper.