There's a difference between social classes, which exist in nearly every country, and a caste system. Castes are hereditary, you are born into a caste.

Very few people are born into tech. Anyone working in San Francisco probably realizes that most people in Bay Area tech weren't even born in the Bay Area. Working in Bay Area tech is a choice, one which requires hard work and quite a lot of luck.

People are born with varying degrees of privilege, which makes it easier for some than others to get a tech job, that isn't a caste system.

I've been on a tech career path since I was a teenager, but with one parent who was a teacher and the other who was a construction worker, it wasn't like I was born into it. I've worked with plenty of people who have made the transition to a tech career later in life. Like one person who said he was tired of digging ditches so he went to tech bootcamp.

The classes in SF are extreme. The pay disparity is too large. It is really hard for a lot of people to get by. But it isn't a caste system.