HNL was axes when SQ received aircrafts which could overfly it through to the mainland USA. HNL was a low-yield destination as people just stopped over enroute to the destinations. It was also cheaper for them (timewise) to just fly direct to the mainland. HNL has never been a major business destination for asian traffic, and hence along with Asiana and Eva Air years later on, you can only get there from around asia on Japan Airlines, Korean Air, Continental and United. I don't even know if Philippine Airlines still fly there.
SQ did fly to Toronto way back in 1981-82. It was their first TransAtlantic route and they were heavily promoting it prior to their launching the New York route. The route was axed not because 'there were no Canadian airline' that didn't want to fly to Singapore, but because SQ was prohibited from taking passengers enroute from Singapore, notably from Vienna and Amsterdam which it had received full traffic rights to do so. Austria and Netherlands had no objections but it was Air Canada who objected because they claimed that SQ infringed on their traffic by taking passengers away from them. Which was interesting for SQ to document their case because neither VIE or AMS at that time was served by Air Canada! AC also had full traffic rights to SIN at that time, with full fifth freedom traffic rights between SIN and BOM! Unfortunately for SQ, the Canadian Govt sided with AC and advised to SQ that if it wanted to serve YYZ, it can only do so without picking up any passengers enroute from SIN. SQ cancelled the route literally within 6 months of starting it. And within months, got the New York route pushed ahead of launch via AMS and FRA with full fifth freedom traffic rights. It was showing AC hey, we don't need YYZ after all.
For years, Singapore and Canada literally had no permenant air agreement between them. It was renewed only on an annual basis. AC had always been in SQ's bad books after that. Boy they must have bitten the bullet by allowing them to codeshare with SQ on the CPH/LHR-YYZ route now just because of the Star Alliance arrangement.