Maybe they did, but their measly $10K or whatever offer wasn't even close to worth it for the business to switch?
I've had that happens with clients - they get some $5K, $10K or even $20K+ offer for their premium .CA (as you know, no one is offering millions for a .CA and Canadian business is cheap as dirt) and they just laugh and do some quick mental gymnastics on how much it would cost them to switch to another domain (stationary, business cards, signage, office accoutrements, legal name change, website, advertising, etc.) not to mention all the lost business and sheer investment in time & effort, and then totally ignore them.
The only way this scenario makes sense is if a Canadian company owns both the .COM and .CA, and gets a life-changing money offer on the .COM and decides to sell - this has happened a few times recently, but the .CA? I don't see any company ponying up the necessary cash to make it worthwhile for the business that currently owns the domain.
The best time to buy is when the domain hits the expired list and all you need to do is outbid the wholesalers.