In cases of such CD-R media failures;

if I was a regularly gigging solo artist,
I'd consider it my responsibility to
include a contact email adress printed in the CD package
offering some kind of practicable online backup
of rar/zip flac files [& md5/sfv etc] for any faulty CD-r's purchased.

I'd find any simple, effective ways to solve problems, despite potential risk
of abuse of trust..