It basically has to do with "consolidator" tickets. CX cannot offer them on line on markets other than from HKG and SIN.

From HKG, the fares are comparable to what agencts in HKG can offer. But it's only in economy.

From SIN, as the government there has legalised consolidator fares, all airlines can sell freely whatever fares they choose on their websites - most of it better than what the travel agents can offer. CX has great fares with hardly any restrictions - which can be booked and ticketed up to 3 hours prior departure.

I've booked it once and will do so again.