Why should David Lowery get paid now for work he did 20-30 years ago? Most of us are lucky to get paid for work we did in the past month, and after that we'll never get paid for that particular bit of work ever again. Imagine if I still got paid, even just a few bucks a month, for all those burgers I flipped back in the 90s? Regular people have to keep working for their paychecks.
In that light it sounds a lot different to complain that work we did 20 years ago doesn't provide the steady income we once thought it would. Times change, and if you want to get paid don't rest on your laurels, keep making stuff people want.