There is a crackdown on falsely promoting junk food as healthy or promoting it to people who don't know better (namely children). Maybe not on YouTube, but in various countries' legislation.
It's not really a fair comparison, though. The main issue with anti-vaccination content is dangerous misinformation, not simply promoting something harmful. The other issue is that the people who fall for this content aren't usually the ones who get hurt, their innocent children are. It would only be a fair comparison if there were a large movement of very influential, powerful, and famous people posting "vegetables cause autism, and Burger King cures it" videos out there to hundreds of millions of viewers and a boom in child obesity tied directly to parents viewing them.
http://news.bbc.co.uk/2/hi/health/6154600.stm
https://www.wsj.com/articles/SB106919100053167300
https://publications.parliament.uk/pa/cm200304/cmbills/110/0... (Section 3)
It's not really a fair comparison, though. The main issue with anti-vaccination content is dangerous misinformation, not simply promoting something harmful. The other issue is that the people who fall for this content aren't usually the ones who get hurt, their innocent children are. It would only be a fair comparison if there were a large movement of very influential, powerful, and famous people posting "vegetables cause autism, and Burger King cures it" videos out there to hundreds of millions of viewers and a boom in child obesity tied directly to parents viewing them.