This industry is very fresh. You should always have double-check code reviews with your team, if not quad-check it. This is why hackathons and bug-bounty programs exist. It should never be the responsibility of one, team work is very important. Everyone is trying to quickly get into the industry and try to make money, however ethical issues should also be kept in mind. The stronger your code is, the better your reputation is, the better your product will be.
Sorry but nobody really does doublecheck by another team anywhere in dev, so def. not in a new industry like crypto...
I respectfully disagree. As a company, you would want to ensure your code is reliable and has been vetted by other professionals.
Your reputation is important if you want to sustain a long term company that provides a service to the world.