The NTSC version was never sold in the US, so I'm sure that limited its appeal to developers. A few may have been sold in Canada.
I think you may be mixing up the CDTV with the CD32, There were defiantly CDTV's sold in the US, I can't see all the ones on ebay from the US as Canadian units brought into the US.
Yes, the CD32 was sold and used a fair bit in Canada from Bank "freebees" (open an account with us and get a free CD32) to driving test terminals.