Not strictly worse, for two reasons: (a) debt-cost cards, and (b) trash-for-benefit cards.

It's close enough to strictly better to be considered strictly better, though. Bridge would be roughly the same strength as Woodcutter otherwise, but that's obviously not the case.

Applying the term "strictly better" for something which is not strictly better in more than just fringe cases is pretty dubious.

Just say something like "most of the times Canal is better the Project version of Key/Treasury" or whatever.

Cards that give +Buy, making cost reduction better than +

_{}: 53

Cards that want cards to cost more, making cost reduction worse than +

_{}: 9

Cards that cost Debt, making cost reduction worse than +

_{}: 9

The cases where cost reduction isn't strictly better than +

_{} is more of a fringe case than the cases where it is. 53 / 394 ~= 13%; and since there are 10 Kingdom cards in each game, the average game will have ~1.3 cards that give +Buys, making cost reduction better than +

_{}. Not exactly a fringe case. Especially when the cards that make cost reduction worse than +

_{} are combined 1/3rd as common as the cards that make cost reduction better.