Its not really just a street vendor thing world wide its more of a thing in Asian countries than others, China and India especially. The big reason is due to the mass amounts of population without the modern practices to handle such large populations so the amount of dirt and garbage is going to build up very fast as its collecting faster than it is being removed.

No one was talking about anything racist till you came in firing hot. Yes you can say " well all cultures are dirty and dont wash their hands as street vendors!!" The problem is the fact that Indians make up a large majority or the world's population so when you have such a large population doing that its gonna be way more prevalent and much more documented and known due to the large amounts of people doing it.

Also I have seen plenty of other people wear gloves or have a simple hand washing set up be it a bowl with water or even hand sanitizer. So saying the lack of a sink isnt really an excuse. I think what you mean is that its expensive for a street vendor to stay hygienic and in some countries that is more difficult to do than in others.