In sci.electronics.repair, on Mon, 24 Jul 2017 15:06:47 +1200,
"~misfit~" wrote:

Once upon a time on usenet bitrex wrote:
On 07/22/2017 05:33 PM, Michael Black wrote:

There was an issue of older CD players not playing CDRW discs. I
forget the details, but after a certain date, CD players didn't seem
to have the problem. So something was changed there. But that's
different from playing MP3s, though for many people it did matter,
since they put MP3s on a CDRW disc and then played that.

CD-RWs required more sensitive optics on the part of the playback
device, CD-Rs however once they were written with PCM audio data
(_not_ mp3 files) and finalized IIRC were essentially the material
equivalent of a commercial Red Book audio CD and should work on any
CD player, even ones from the 1980s.

Actually CDRs are much less reflective than 'pressed' CDs and as such some
older CD players don't have the laser power needed to get a good (reflected)
signal. This was common knowledge back when CDRs first became affordable and
people would have trouble with their older players not playing them (or not
playing them reliably). Back then some players started being sold as being
CDR compatible but after a while it became taken for granted and the badging
vanished.

So this accounts for my original question.

CDRW discs are even less reflective than CDRs.