My responsibilities are to decide what we build and why. I'm also the shit umbrella for the developers, and end up having to speak with clients. Ultimately it's me who is held responsible for the success / failure of the product.
The myth of project / product people being paid more may be true in LargeCorp, Inc. but in Startup LLC., the developer is king.
The confusion might come from large companies where PMs tend to be more senior to a lot of the development team. But once a engineer matures and gains experince they will pass them. I my experience, it's very common to make more than the person who manages you.
From my experience - I'm basing this on approximately 80 positions at 4 different companies - PMs are paid $55k - $80k while engineers/developers are paid $75k - $140k.
Hmmm, makes me wonder about this meme...