I don't know about "normal" blind people who are not software developers like me but I find most of the web accessible. I was able to successfully complete the R Programming course on Coursera with no sited help. I can do online banking, ordering off amazon, etc. One accessibility issue with Netflix was that they did not have audio description for video but this is getting better.

Because only a very small percentage of those that create the content are disabled themselves.

Piggybacking on this answer, it's also because there is a cost (money, time, knowledge, dev sophistication, etc) to doing it that way.

When people don't see something as an issue b/c they aren't disabled themselves, and it would take extra time / consideration / money to support disabled folks, people won't do it.

That is why in the US we had to legislate handicap accessibility in the real world. People don't build ramps unless they have to.