We have a similar one to this when someone is incompetent which is “They couldn’t organise a pissup in a brewery”.

Yeah they’re all part of the Brassica family. Canola is a bred cultivar of Rapeseed with low levels of erucic acid suited for human consumption and very widely grown so while not completely synonymous with Rapeseed using the term Canola is usually correct especially with respect to the cooking oil.