Canada has long had fewer stations per market than comparably sized US markets, so Canadian station generally have a very fertile ad sales environment at home.
CKLW was the exception as, other than one 1-A clear channel, in the mid and late 60's it did not have big signals. WJR and WWJ were, at that time, committed to full service and MOR formats, and there was Top 40 on pretty dreadful signals like Keener and Storer's "build a few more towers" WJBK.
And the areas stations in Vancouver could cover in WA are lesser populated towns like Blaine, not Seattle metro.
The situation that originated Canada's rules on advertising on foreign stations began when McLendon (the KLIF McLendon) used a TV station in Pembina, ND, to sell advertising in Winnipeg, Manitoba. The local broadcasters did not like it, the CBC did not like it and that gradually resulted in restrictions on cross border advertising.
As you and others here are possibly aware, for a period of about twenty years, I was in Canada roughly every two or three monthss. I really enjoyed it, because my competitors tried to cover the territory on the phone, so I pretty much had the entire country all to myself. And my Canadian customers loved reaching customers in America because they all did business in U.S, dollars, but paid their employees and suppliers in U.S. dollars. (Exchange rate typically mean the Canadian dollar was worth about 80 cents U.S.)
Anyway, over the course of my time up there, not only did I meet and work with a lot of great people, but I also got pretty familiar with how broadcasters operated up there. One of the first things I noticed, aside from Can Con rules, was that Canadian Cable companies pre-empted U.S. network TV shows anytime the same program was being fed to both countries. They just dropped the U.S. signal and replaced it with the Canadian one on the same cable channel. I also remember U.S. TV stations like Channel 12 in Pembina, North Dakota, (I forget the calls, maybe KCND?) that basically was intended for the purpose of extracting advertising revenue from Winnipeg. WPTZ in Plattsburgh, New York, Channel 5 had at least some aspects of that business model involving Montreal. On the radio side, to this day, there are American versions of border blasters with brokered basically religious programming aimed at Canadian cities. WTOR in Youngstown, NY is a highly directional daytimer on 770 from Youngstown, New York beamed directly across Lake Ontario at Toronto. The major lobe is listenable for about 100 miles beyond the Toronto metro. I believe WTOR is owned by Baruch Broadcasting....a group owner of brokered stations.
For me, the most revealing comment regarding Can Con came from Burton Cummings, lead singer of the Guess Who, who also hosted afternoon drive on CKY in Winnipeg for a few years in the 1990s. One afternoon, I was in the car driving back to Minneapolis and he was talking with his guest about Can Con. He said that when Can Con was first launched, he, and most of the Community actually opposed it on grounds that it was an infringment on free speech. But he went on to say that as years passed, he grudgingly came to the realization that the Can Con rules helped a number of succesful careers....even if only domestically....for scores of performers who might otherwise only be playing local gigs in bars, weddings, etc.
