Why is WCA low ?
When you only have one major buyer, they pay what they want. Who doesn't get that? Oh yeah, the Canadian government, that's who! What a bunch of toads.
The differential should decreaase when a pipeline comes online in 18 months or so. OMG!. Lol. Read this one: https://ca.reuters.com/article/businessNews/idCAKBN1KO21K-OCABS
Here's a bit dated WCS report from EIA.
https://www.eia.gov/todayinenergy/detail.php?id=36032
With Venezuela OIl dropping off and Canadian crude imports picking up, WCS should be commanding a better price.