The vast majority of people don't know about it. Many people encounter it all the time, but they don't understand the "why" behind what's happening. Like, they know that when the battery in their iPhone dies, they have to throw it out and buy a new one. They might think Apple are assholes for this, but they don't realize that this is because they don't have the right to repair their own phones, and they certainly don't know that it's because of section 1201 of the DMCA making bypassing access controls a felony.

A lot of people fondly remember a grandfather or an aunt who was a whiz at repairing things. They talk about the modern world where everything is just thrown away, and think it's a sad state of affairs. But, they probably think it's just because electronics have become complicated. They don't realize that it's section 1201 that's making it illegal to repair things.

Other people, particularly people over 40, remember when MySpace fumbled and Facebook took over. They remember when the Internet used to be better, and maybe are vaguely curious if that same thing is going to happen to Facebook. What they don't realize is that what Facebook did to MySpace involved bypassing an access control mechanism in order to bridge the two networks and slowly migrate people over to Facebook. The reason it wouldn't happen today is that anybody who tried to do to Facebook what Facebook did to MySpace would be attacked by an army of Facebook lawyers, backed by section 1201.

As for young people, they don't know any better. The DMCA is from 1998, so for anybody under 26 it has been there for their entire lives. That's just how the world works.