The title could have meant, "Ads Urging Canadians to Oppose Climate Laws [That Were] Paid for by Gas Industry".

Given big industry buys laws all the time, I had to spend some time figuring it out and my first impression was the wrong one. I don't think that's great for a headline. We don't have to save column inches anymore, we can have more descriptive headlines.

From the article a clearer headline would read, "Ads Urging Canadians to Oppose Climate Laws [Were] Paid for by Gas Industry". Or they could say, "Ads Paid for by Gas Industry Urge Canadians to Oppose Climate Laws". That puts the industry's lobbying right up front.